The speedy, bumpy, sometimes scary slide downhill is one of the outdoor winter activities that youths and adults have always enjoyed. It can be fun, but every year thousands of youths and adults are injured sledding down hills in city parks, streets and resort areas. Most of these injuries are preventable.

Incidence of Injury
According to the U.S. Consumer Product Safety Commission, there were more than 52,000 sledding, snow tubing, and tobogganing-related injuries treated at hospital emergency rooms, doctors' offices and clinics in 2014. The total medical, legal and liability, pain and suffering, and work loss-related costs were close to $2 billion.

The majority of injuries happen to youths age 14 and younger, especially in the run outs at the end of the sledding path. Adult supervision is needed to make sure that children sledding down a hill don't collide with children in the run outs and that the end of the sledding path isn't in a street or parking lot, pond or other hazardous area. Some of the injuries can be serious enough to cause lifelong disability or death. When a sled hits a fixed object such as a tree, rock or fence, the rider may suffer head and neck injuries. Helmets help prevent head injuries and should be worn by sledders under 12 years old.

Young children are very vulnerable to injuries. They have proportionally larger heads and higher centers of gravity than older children and teens. Their coordination has not fully developed and they can have difficulty avoiding falls and obstacles.

Do Not Sled on Public Streets
The first big snowfall of the winter season often tempts youths to sled down sloping streets where they may be hit by cars and trucks or slam into parked vehicles, curbs, and fences.

Speeding down hills in parks that are not designed for sledding is risky. Individuals may have to dodge trees and rocks.

Sit in a Forward-Facing Position
Some youths may run with their sleds and leap forward in a "belly flop" that does not give them control of where they are sliding.

Do not sled on plastic sheets. They cannot be steered and can be pierced by sharp objects.

Essential Precautions

• Sledding should be done only in designated and approved areas where there are no trees, posts, fences or other obstacles in the sledding path. The sledding run must not end in a street, drop off, parking lot, pond or other hazard.
• Parents or adults must supervise children in sledding areas to make sure the sledding path is safe and there are not too many sledders on the hill at the same time or at the end of the run to avoid collisions.
• No one should sled headfirst. All participants should sit in a forward-facing position, steering with their feet or a rope tied to the steering handles of the sled.

Preferred Precautions

• Young children should wear a fitted helmet while sledding.
• The sled should have runners and a steering mechanism, which is safer than toboggans or snow disks.
• Sledding in the evening should only be done in well-lighted areas.
• Plastic sheets or other materials that can be pierced by objects on the ground should not be used for sledding.
• Sledders should wear layers of clothing for protection from injuries and cold.
  
  Source: American Academy of Orthopaedic Surgeons 

When an unexpected accident happens turn to Urgent Care at Orthopedic Associates of Lancaster. With immediate access to orthopedic specialists, quick evaluations and on-site x-rays and MRI's OAL is here for all of your orthopedic needs.

Common Basketball Injuries

The fast-paced action of basketball can cause a wide range of injuries, most often to the foot, ankle, and knee. Sprained ankles and knee ligament tears are common. Basketball players are also at risk for jammed fingers and stress fractures in the foot and lower leg.

Several strategies can help to prevent basketball injuries — from careful inspection of the play area to using proper passing techniques.

Proper Preparation for Play

Maintain fitness. Be sure you are in good physical condition at the start of basketball season. During the off-season, stick to a balanced fitness program that incorporates aerobic exercise, strength training, and flexibility. If you are out of shape at the start of the season, gradually increase your activity level and slowly build back up to a higher fitness level.

Warm up and stretch. Always take time to warm up and stretch. Research studies have shown that cold muscles are more prone to injury. Warm up with jumping jacks, stationary cycling or running or walking in place for 3 to 5 minutes. Then slowly and gently stretch, holding each stretch for 30 seconds.

Hydrate. Even mild levels of dehydration can hurt athletic performance. If you have not had enough fluids, your body will not be able to effectively cool itself through sweat and evaporation. A general recommendation is to drink 24 ounces of non-caffeinated fluid 2 hours before exercise. Drinking an additional 8 ounces of water or sports drink right before exercise is also helpful. While you are exercising, break for an 8 oz. cup of water every 20 minutes.

Focus on Technique

• Play only your position and know where other players are on the court to reduce the chance of collisions.
• Do not hold, block, push, charge, or trip opponents.
• Use proper techniques for passing and scoring.
• Do not forget sportsmanship.

Ensure Appropriate Equipment

• Select basketball shoes that fit snugly, offer support, and are non-skid.
• Ankle supports can reduce the incidence of ankle sprains.
• Protective knee and elbow pads will protect you from bruises and abrasions.
• Use a mouth guard to protect your teeth and mouth.
• If you wear glasses, use safety glasses or glass guards to protect your eyes.
• Do not wear jewelry or chew gum during practice or games.

Ensure a Safe Environment
• Outdoor courts should be free of rocks, holes, and other hazards. Inside courts should be clean, free of debris, and have good traction.
• When playing outside, environmental conditions must be considered. Players should avoid playing in extreme weather or on courts that are not properly lighted in the evening.
• Baskets and boundary lines should not be too close to walls, bleachers, water fountains, or other structures. Basket goal posts, as well as the walls behind them, should be padded.

Prepare for Injuries
• Coaches should be knowledgeable about first aid and be able to administer it for minor injuries, such as facial cuts, bruises, or minor strains and sprains.
• Be prepared for emergencies. All coaches should have a plan to reach medical personnel for help with more significant injuries such as concussions, dislocations, contusions, sprains, abrasions, and fractures.

Safe Return to Play
• An injured player's symptoms must be completely gone before returning to play. For example:
• In case of a joint problem, the player must have no pain, no swelling, full range of motion, and normal strength.
• In case of concussion, the player must have no symptoms at rest or with exercise, and should be cleared by the appropriate medical provider.

Because many young athletes are focusing on just one sport and are training year-round, doctors are seeing an increase in overuse injuries. The American Academy of Orthopaedic Surgeons has partnered with STOP Sports Injuries to help educate parents, coaches, and athletes about how to prevent overuse injuries. 

Specific tips to prevent overuse injuries include:
• Limit the number of teams in which your child is playing in one season. Kids who play on more than one team are especially at risk for overuse injuries.
• Do not allow your child to play one sport year round — taking regular breaks and playing other sports is essential to skill development and injury prevention.

Source: US Consumer Product Safety Commission (CPSC), 2009
https://www.orthoinfo.org/en/staying-healthy/basketball-injury-prevention/

by Gregory A. Tocks, D.O. 

Orthopedic Associates of Lancaster Ltd.

INTRODUCTION

Since long-term survivors are at risk of needing a revision procedure, the durability of their prostheses, particularly at the bearing surfaces, is a major concern. Because of the stresses at the hip joint, the ideal component should minimize wear, maintain stability, and preserve longevity. This article provides an outline of the common prosthetic bearing surfaces for total hip replacement, their comparative wear characteristics, advantages, and disadvantages. 

The techniques of hip surgery are not the focus of this article, but for the interested reader, the common surgical approaches and methods of hip arthroplasty are illustrated on the websites of one of the prosthesis manufacturers.3

PROBLEM OF WEAR IN POLYETHYLENE ACETABULAR LINERS

Fig. 1 Illustration of pink ceramic femoral head, white polyethylene liner, and metal acetabular cup. The femoral stem prosthesis is not shown. (From Depuy Pinnacle Polyethylene technique guide.3).  

Fig. 2 A: Acetabular cup with cobalt-chromium femoral head and highly crossed-linked polyethylene liner; B: Acetabular cup with ceramic femoral head and highly crossed-linked polyethylene liner; C: Acetabular cup with ceramic femoral head and ceramic liner.

The acetabular liner is a polyethylene implant that is generally impacted into the acetabular cup. During the life of a total hip arthroplasty, wear primarily affects the polyethylene acetabular liner. The

Consequences of Wear

The wearing process in polyethylene liners produces small particles of polyethylene debris. The immune system responds by releasing macrophages and associated cytokines (e.g. TNF-α), which activate osteoclasts that produce osteolysis around the hip joint (Fig. 3).

 

Fig. 3. CT scan coronal (A) and axial (B) images showing significant osteolysis behind the previously implanted acetabular cup. 

The loss of bone causes micromotion of the hip implants, and further potentiates osteolysis. As a result of the osteolysis and wear, patients are at increased risk of several consequences, including periprosthetic fractures from simple falls or minor trauma, aseptic loosening of the prosthesis, or dislocation of the prosthesis.

Conventional Polyethylene and Highly Crossed-Linked Polyethylene

The polyethylene component has gone through two generations, termed “conventional polyethylene,” (CP) and “highly crossed-linked polyethylene” (XPE). In CP, radiation is used to form the hydrocarbon bonds, and the irradiation produces free radicals. If oxygen binds at the site of free radical formation, the resulting oxidation degrades the material’s properties. CP is irradiated with doses of 25-40 kGy,* and XPE is irradiated with doses of 50-100 kGy. The higher dose increases the cross-linking potential between free radicals, but radiation doses greater than 100 kGy compromise the mechanical properties of the material. 

Another step in the process to reduce free radicals and oxidation is thermal stabilization, or heating. In the production of polyethylenes, various commercial companies use different types of radiation, radiation doses, and methods of stabilization, machining, and terminal sterilization. 

Wear is termed linear wear (femoral head penetration into the liner), and volumetric wear (amount of material lost). Linear wear is assessed in clinical studies, and volumetric wear in laboratory studies. Osteolysis has a higher propensity to occur with linear wear greater than 0.10 mm/yr and volumetric wear greater than 80 mm3/yr.4 Laboratory simulator studies done prior to commercial release demonstrated less wear for XPE compared with CP.5-11 Those in-vitro wear studies also demonstrated that with XPE, the degree of wear that occurs is not related to the size of the prosthetic femoral head selected, nor to the initial thickness of the polyethylene liner. (The importance of this characteristic will become clear in a discussion below.) 

XPE was introduced into clinical practice in 1999 with the expectation that lower wear rates in-vitro would translate to lower wear rates in vivo. Two randomized clinical studies followed patients for five years after total hip arthroplasties with XPE or CP.12 Both studies concluded that, compared with CP, XPE had significantly fewer penetrations of the liner by the femoral head. The wear rate for XPE decreased by more 95% compared with the wear rates for CP, and tended to plateau after one year. 

Another study found that five years after total hip arthroplasty there was significantly less osteolysis on CT scan with XPE compared with CP (28% versus 80%).13 Multiple other studies have since confirmed a reduction in wear rates for XPE compared with CP, which has translated into less osteolysis and aseptic loosening in total hip arthroplasties with XPE.

FEMORAL HEAD AND ACETABULAR LINER BEARINGS Cobalt-Chromium & Crossed Linked Polyethylene (XPE)

The most common femoral head composition used in total hip arthroplasty is made of a cobalt-chromium (CoCr) metal alloy. As a result, the most widely used combinations in the U.S. are metal-on-polyethylene bearings (Fig.3), and most studies that compared CP to XPE wear used CoCr femoral heads. In 2013, the Swedish registry detected a trend toward fewer cup/liner revisions with the use of XPE, compared with an increase in the previous years when CP was used.14 In 2014, the Australian arthroplasty registry also noted that, as time progressed, there was a lower revision rate with XPE compared with CP.15 

In high risk patients, larger femoral heads are used sometimes to decrease the risk of impingement of the femoral head or neck of the femoral prosthesis on the edge of the acetabulum or polyethylene liner. These contacts may produce a lever arm that causes a dislocation. To accommodate the larger femoral head, a thinner polyethylene liner would be needed, but as noted earlier, multiple studies have demonstrated that for XPE, thickness of the polyethylene liner does not affect the wear rate. A thinner XPE cup might also raise concern about fracture, but this also has not been an issue except in those acetabular cups placed more vertically, anteverted, or with a rim thickness at the locking mechanism < 4 mm.

Since most non-cemented femoral prostheses are constructed of titanium, there has been concern recently about the bearing coupling between the CoCr femoral head and the titanium femoral prosthesis. This mixed metal construct may increase the risk of fretting** and corrosion at the modular junction, a process termed trunnionosis (Fig. 4). (The trunnion is the tapered portion of the femoral stem prosthesis where the femoral head is impacted during implantation.)

 

Fig. 4 Example of trunnionosis of a cobalt chromium femoral head and the tapered portion of the femoral prosthesis. With CoCr femoral heads, there have been reports of corrosion at the trunnion, metal wear at the trunnion, and adverse local tissue reactions from the metal debris. As a result, it has been proposed that ceramic femoral heads be used to avoid these reactions. However, registries have not reflected a statistically significant difference in revision rates between ceramic or CoCr femoral heads with XPE liners. Also, ceramic femoral heads typically are significantly more expensive than CoCr femoral heads and may not be cost effective. 

Studies have also revealed that XPE liners are more tolerant of acetabular component malposition. Together with the low wear characteristics of XPE, the cheaper cost of CoCr femoral heads, and the ability of metal-on-XPE bearings to withstand minor malposition, CoCr-XPE bearings should be the predominant couple in current total hip arthroplasties.

Ceramic Bearings

Ceramic bearings were first used in clinical practice in the 1970s. The ceramic components are fabricated from pure alumina, zirconia, and alumina matrix composite powder. In total joint replacement, ceramic constructs are available for both the femoral head and the acetabular liner. Ceramic constructs have stronger mechanical properties and lower wear rates.16,17 Their hard structures and smoothly polished surfaces provide higher resistance to wear, and minimize frictional forces because of their hydrophilic properties.18

Not only do ceramic-on-ceramic constructs have the lowest wear rate amongst all bearings, but they also cause less soft tissue reactions when compared to metal-on-polyethylene and metal-on-metal bearings.19 Because a ceramic component is not a metal alloy, there is less trunnionosis with the combination of a ceramic femoral head and a titanium femoral prosthesis, and less chance for metal debris and damage to the titanium trunnion. Also, the lack of metal debris makes ceramic femoral heads beneficial in patients with metal hypersensitivity.

In-vivo studies have demonstrated excellent wear rates over a 10-year period for both ceramic-on-polyethylene,20-24 and ceramic-on-ceramic bearings,21-22,25-29 with no statistically significant difference in osteolysis, wear rates, or implant failure.22-24 

Nonetheless, first-generation ceramic components had higher rates of component fracture than XPE liners with CoCr femoral heads. Fracture is catastrophic because it results in multiple fragments that may lead to third body wear and damage of the femoral prosthesis. Fortunately, the newest generation of mixed oxide ceramic materials has greatly reduced the risk of fracture to roughly 0.003% and 0.03% for Delta ceramic heads and liners, respectively.30

The various factors that influence the risk of ceramic femoral head fractures include the cleanliness of the trunnion prior to head impaction, the amount of force used to impact the head on the trunnion, and the size and length of the femoral head. (Smaller heads and shorter necks have a higher risk of fracture.) 

Ceramic-on-ceramic hip constructs are also associated with increased squeaking. The Australian National Joint Registry noted a 4.2% rate of squeaking with this construct.31 Squeaking can occur with every step, or with deep flexion, and is likely caused by malposition of the acetabular component with excessive inclination and anteversion. Squeaking may also occur with the loss of the fluid film lubricating the joint. Component malposition is also a factor, as it may result in increased loading against the edge of the cup. Care must be taken to avoid this complication because it may produce embarrassment and anxiety for the patient, and litigation against the surgeon. There is no clear evidence that squeaking increases the wear rate of the implant, though there are suggestions that it may. In addition, ceramic heads have traditionally been significantly more expensive than CoCr, and their cost effectiveness is debatable.

Ceramicized Femoral Heads

Zirconium is a hard metal with properties like titanium. It is not found naturally as a metal, but can be refined, through a complex process, from zirconium silicate (ZrSiO4). However, Zirconium oxide (ZrO2) is not a metal but a ceramic. It was first used clinically in total hip arthroplasties in approximately 2003 as a zirconium oxide, ceramic, outer surface of approximately 5 μm on a zirconium metal femoral head (Fig. 5).

 

Fig. 5 Acetabular cup with highly crossed-linked polyethylene liner and ceramicized femoral head.

This ceramic outer surface has similar mechanical properties to a fully ceramic bearing, including a smooth surface, increased scratch resistance, and increased hardness when compared to CoCr. In vitro studies confirm that ceramicized zirconium femoral heads share the improved resistance to wear of fully ceramic heads with polyethylene, especially with XPE.32 The Australian Joint Registry reported a low revision rate of 3.3% at 11 years with this bearing couple.33 However, in-vivo studies vary when comparing XPE with CoCr or ceramicized heads. Some studies show statistically significant differences in wear rate, and others demonstrate no difference.34-36

Because of its zirconium alloy core, this composite will not fracture like fully ceramic heads. However, the oxide surface may be damaged if it contacts other metal surfaces, such as the rim of the acetabular metal shell during joint reductions and dislocations. Ceramicized femoral heads also have a higher resistance to fretting and corrosion of the trunnion compared to CoCr, so they may be a suitable option if there is concern about trunnionosis. 

Like ceramic heads, ceramicized heads are also a viable option in patients with metal hypersensitivity since they avoid metal debris and trunnionosis at the bearing junction. Like the all-ceramic heads, however, ceramicized heads are significantly more expensive than CoCr femoral heads. Also, only one company currently manufactures this product, and it should therefore only be used with this company’s compatible femoral prosthesis.

In sum, ceramicized heads are a good option because of their improved wear characteristics and good in-vivo results, but their increased cost, and production by only one manufacturer, limits their widespread use.

METAL-ON-METAL FEMORAL HEAD AND LINER

As discussed throughout this article, a primary concern in total hip replacements is the wear rates of bearing materials. A metal-on-metal (MoM) bearing includes a CoCr metal head and a metal acetabular liner. (Fig. 6)

 

Fig. 6. Metal-on-metal hip prosthesis with femoral stem, cobalt chromium femoral head, metal liner, and metal acetabular cup. 

Traditional stemmed MoM hip replacements (and later resurfacings) were first introduced in the 1990s because they offered lower wear rates. For younger patients who need total hip replacement for osteoarthritis, longevity of the implant is a particularly important characteristic. It is estimated that since 1996, more than 1 million MoM implants have been inserted worldwide. MoM bearings can result from traditional hip replacement with a stemmed femoral prosthesis (Fig. 7B), or resurfacing of the femoral head with a metal cap (Fig. 7A), in which case more bone is preserved.

 

Fig. 7. Radiographs of metal-on-metal prosthesis. A: Hip resurfacing prosthesis; B: Stemmed metal-on-metal total hip replacement.

The benefits of MoM bearings compared with metal-on-polyethylene include not only lower volumetric wear rates, but also greater stability of the implant; because metal inserts are thinner than polyethylene liners, larger femoral head sizes can be used. 

However, the use of MoM bearings in stemmed hip replacements is not recommended in the U.S. because there are reports in the literature of poor outcomes. When MoM bearings are inserted in patients who are more than 55 years old, have larger femoral heads, or have acetabular cups placed in excessive inclination, they have a higher risk of revision than polyethylene and ceramic bearings.36-38 

Soft tissue reactions from the metal ions of the MoM bearings are the key issues in failure of the implants and associated complications. The metal ions cause adverse local tissue reactions (ALTRs), osteolysis, enlarged bursae, effusions, creation of pseudotumors, destruction of the abductor muscles, and necrosis. (Fig. 8)

 

Fig. 8. A: MARS MRI axial image with pseudotumor (arrow) anterior to the femur and metal-on-metal prosthesis; B: Intraoperative image of previous metal-on-metal prosthesis causing extensive metallosis and soft tissue destruction.

A lymphocyte dominated immunologic response occurs in the tissue, known as aseptic lymphocyte-dominant vasculitis-associated lesions (ALVAL). Unfortunately, it is not possible to predict which patients will have these reactions to metal ions. Some patients have symptoms, others have none, but it is generally recommended that even asymptomatic patients should be evaluated yearly with radiographs to assess osteolysis and blood levels of cobalt and chromium ions. Metal ion levels > 7 ppb (parts per billion) are considered elevated, and should instigate advanced imaging. Metal artifact reduction sequence (MARS) MRI helps assess for presence of pseudotumors and integrity of the abductor and gluteal muscles.

Optimum treatment of asymptomatic patients is debated. Treatment of symptomatic patients is multi-factorial but commonly involves a revision total hip replacement. Placement of metal-on-polyethylene or ceramic-on-polyethylene bearing constructs are generally recommended for stable acetabular and femoral prostheses. 

Many companies have recalled their MoM stemmed hip replacements because of these unfavorable outcomes. Therefore, hip resurfacing is the only recommended MoM bearing, and should be reserved for younger patients with preserved femoral head bone stock. However, this operation is not typically performed by most orthopedic surgeons.

CONCLUSION

Substantial progress has been made in the bearing components of total hip replacements in the past 30 years. Newer highly crossed-link polyethylene liners have significantly decreased wear rates when compared with conventional polyethylene. Cobalt chromium femoral heads and highly crossed linked polyethylene liners are the dominant bearing couple used in the United States, due to excellent follow-up studies. Ceramic and ceramicized femoral heads have lower wear rates, but they are more costly. They may be viable options in younger patients, and those with metal hypersensitivities. Stemmed metal-on-metal hip replacements have largely been removed from the U.S. market due to post-operative complications, and the need for revision surgery. The ultimate goal will be to create a bearing couple with minimal complications and increased durability.* Gy = Gray, the International Unit of absorbed ionizing radiation. It is derived from the applied energy (in Joules) and the mass of the affected matter (in Kg). 

kGy = thousands of units. ** Fretting: A special wear process that occurs at the contact area between two materials under load that are subjected to relative motion by vibration or some other force.

REFERENCES

1. Wolford M, Palso K, Bercovitz A: Hospitalization for total hip replacement among inpatients aged 45 and over: United States, 2000-2010. Centers for Disease Control and Prevention https://www.cdc.gov/nchs/data/databriefs/db186.htm 

2. Kurtz S, Ong K, Lau E, et al: Projections of primary and revision hip and knee arthroplasty in the United States from 2005 to 2030. J Bone Joint Surg Am 2007;89(4):780-785. 

3. Depuy Pinnacle Polethylene technique guide: 

4. Hammerberg EM, Wan Z, Dastane M, et al: Wear and range of motion of different femoral head sizes. J Arthroplasty 2010;25(6):839-843. 

5. Estok DM II, Burrough BR, Muratoglu OK, et al: Comparison of hip simulator wear of 2 different highly crossed-linked ultra high molecular weight polyethylene acetabular components using both 32- and 38-mm femoral heads. J Arthroplasty 2007;22(4):581-589. 

6. Muratoglu OK, Rubash HE, Bragdon CR, et al: Simulated normal gait wear testing of a highly crossed-linked polyethylene tibial insert. J Arthroplasty 2007;22(3):435-444. 

7. Laurent MP, Johnson TS, Crowninshielf RD, et al: Characterization of a highly crossed-linked ultrahigh molecular-weight polyethylene in clinical use in total hip arthroplasty. J Arthroplasty 2008;23(5):751-761. 

8. Ito H, Maloney CM, Crowninshield RD, et al. In vivo femoral head damage and its effect on polyethylene wear. J Arthroplasty 2010; 25(2): 302-308. 9. Shen FW, Lu Z, McKellop HA: Wear versus thickness and other features of 5 MRAD crosslinked UHMWPE acetabular liners. Clin Orthop Relat Res 2011; 469(2): 395-404. 

10. McKellop H, Shen FW, DiMaio W, et al. Wear of gamma-crosslinked polyethylene acetabular cups against roughened femoral balls. Clin Orthop Relat Res 1999; 3369:73-82. 

11. McKellop HA, Shen FW, Lu B, et al. Effect of sterilization method and other modifications of the wear resistance of acetabular cups made of ultra-high molecular weight polyethylene: A hip simulator study. J Bone Joint Surg Am 2007;89 (10):2212-2217. 

12. Digas G, Karrholm J, Thanner J, et al. 5-year experience of highly crossed-linked polyethylene in cemented and uncemented sockets: Two randomized studies using radiostereometric analysis. Acta Orthop 2007;78(6):746-754. 

13. Leung SB, Egawa H, Stepniewski A, et al. Incidence and volume of pelvic osteolysis at early follow-up with highly crossed-linked and noncross-linked polyethylene. J Arthroplasty 2007;22(6, Suppl 2):134-139 

14. Swedish Hip Arthroplasty Register: Annual Report 2013. https://registercentrum.blob.core.windows.net/shpr/r/Annual-report-2013-HJnnK8Tie.pdf 

15. Australian Orthopaedic Association: National joint replacement registry annual report 2014. https://aoanjrr.sahmri.com/en/annual-reports-2014 Accessed on 6/25/18 

16. Campbell P, Shen FW, McKellop H: Biologic and tribologic considerations of alternative bearing surfaces. Clin Orthop Relat Res 2004;418:98-111. 

17. Macdonald N, Bankes M: Ceramic on ceramic hip prostheses: A review of past and modern materials. Arch Orthop Trauma Surg 2014;134(9):1325-1333. 

18. Di Puccio F, Mattei L: Biotribology of artificial hip joints. World J Orthop 2015;6 (1):77-94. 

19. Esposito C, Maclean F, Campbell P, et al. Periprosthetic tissues from third generation alumina-on-alumina total hip arthroplasties. J Arthroplasty 2013;28(5):860-866. 

20. So K, Goto K, Kuroda Y, et al. Minimum 10-year wear analysis of highly cross-linked polyethylene in cementless total hip arthroplasty. J Arthroplasty 2015; 30(12):2224-2226. 

21. Epinette JA, Manley MT: No differences found in bearing related hip survivorship at 10-12 years follow-up between patients with ceramic on highly cross- linked polyethylene bearings compared to patients with ceramic on ceramic bearings. J Arthroplasty 2014;29(7): 1369-1372. 

22. Kim YH, Park JW, Kulkarni SS, et al. A randomised prospective evaluation of ceramic-on-ceramic and ceramic-on-highly cross-linked polyethylene bearings in the same patients with primary cementless total hip arthroplasty. Int Orthop 2013;37(11): 2131-2137. 

23. Nakashima Y, Sato T, Yamamoto T, et al. Results at a minimum of 10 years of follow- up for AMS and PerFix HA-coated cementless total hip arthroplasty: Impact of cross-linked polyethylene on implant longevity. J Orthop Sci 2013;18(6): 962-968. 

24. Fukui K, Kaneuji A, Sugimori T, et al. Wear comparison between conventional and highly cross-linked polyethylene against a zirconia head: A concise follow-up, at an average 10 years, of a previous report. J Arthroplasty 2013; 28(9):1654-1658. 

25. Chana R, Facek M, Tilley S, et al. Ceramic-on-ceramic bearings in young patients: Outcomes and activity levels at minimum ten-year follow-up. Bone Joint J 2013;95-B(12): 1603-1609. 

26. Synder M, Drobniewski M, Sibinski M: Long-term results of cementless hip arthroplasty with ceramic-on-ceramic articulation. Int Orthop 2012;36(11): 2225-2229. 

27. Streit MR, Schröder K, Körber M, et al. High survival in young patients using a second generation uncemented total hip replacement. Int Orthop 2012;36(6): 1129-1136. 

28. Solarino G, Piazzolla A, Notarnicola A, et al.Long-term results of 32-mm alumina- on-alumina THA for avascular necrosis of the femoral head. J Orthop Traumatol 2012;13(1):21-27. 

29. Sugano N, Takao M, Sakai T, et al. Eleven- to 14-year follow-up results of cementless total hip arthroplasty using a third-generation alumina ceramic-on-ceramic bearing. J Arthroplasty 2012;27(5):736-741. 

30. Massin P, Lopes R, Masson B, et al. French Hip & Knee Society (SFHG): Does Biolox Delta ceramic reduce the rate of component fractures in total hip replacement? Orthop Traumatol Surg Res 2014;100(6 suppl):S317-S321. 

31. Own Dh, Russell NC, Smith PN, et al, An estimation of the incidence of squeaking and revision surgery for squeaking in ceramic-on-ceramic total hip replacement: A meta-analysis and report from the Australian Orthopaedic Association National Joint Registry. Bone Joint J 2014;96-B(2):181-187. 

32. Good V, Ries M, Barrack RL, et al. Reduced wear with oxidized zirconium femoral heads. J Bone Joint Surg Am 2003;85-A(suppl 4):105-110. 

33. Australian Orthopaedic Association: National joint registry annual report 2015. https://aoanjrr.sahmri.com/en/annual-reports-2015 Accessed 6/27/18 

34. Morison ZA, Patil S, Khan HA, et al. A randomized controlled trial comparing Oxinium and cobalt-chrome on standard and cross-linked polyethylene. J Arthroplasty 2014;29(9suppl):164-168. 

35. Jassim SS, Patel S, Wardle N: Five-year comparison of wear using oxidized zirconium and cobalt-chrome femoral heads in total hip arthroplasty: A multicenter randomized controlled trial. Bone Joint J 2015;97-B(7):883-889. 

36. Karidakis GK, Karachalios T: Oxidized zirconium head on crosslinked polyethylene liner in total hip arthroplasty: A 7- to 12-year in vivo comparative wear study. Clin Orthop Relat Res 2015;473(12):3836-3845. 

37. Australian Orthopaedic Association: National joint registry annual report 2010. https://aoanjrr.sahmri.com/en/annual-reports-2010 

38. National Joint Registry for England and Wales: Seventh Annual Report. 2010. http://www.njrcentre.org.uk/NjrCentre/Portals/0/NJR%207th%20Annual%20Report%202010.pdf

HEAT SAFETY

By Michael W. Gish, M.D.

Summer has just officially arrived, and with it comes the promise of hotter weather. While many enjoy the warmth of summertime, summer’s hot temperatures (and humidity) can lead to potentially dangerous health issues when training and competing.

Exertional Heat Illness is a spectrum of conditions that can run the gamut from dehydration, heat cramps, and heat exhaustion to a potentially life-threatening condition known as Exertional Heat Stroke (EHS). Prevention, as well as knowing the early warning signs of Exertional Heat Illness, is the best way to combat these conditions. Prevention involves several factors, including heat acclimatization, adequate hydration, and proper training modifications based on monitoring environmental conditions through the Wet Bulb Globe Temperature (WBGT) — a more accurate measure of potential heat stress than just temperature alone. The WBGT is a measure of the heat stress in direct sunlight, which takes into account temperature, humidity, wind speed, sun angle, and cloud cover (solar radiation). This differs from the heat index, which only takes into consideration temperature and humidity and is calculated for shady areas. There are specific WBGT monitors as well as several phone apps designed to measure the WBGT. 

ACCLIMATIZATION

Acclimatization is the body’s natural adaptation to exercising in the heat. While there are many
recommendations on how to do this, general guidelines include avoiding the hottest part of the day (11am-4pm) for training sessions, if possible, and gradually increasing the amount of time spent training in the heat over the course of a 10-14 day period of time.

HYDRATION

Adequate hydration begins before the training session or competition. Athletes should be regularly hydrating throughout the day and should also plan to drink 12-16 ounces of fluid approximately 30 minutes before getting to the field. During activity, periodic drinking should be enforced even if the athlete does not “feel” thirsty. It is recommended that every 15-20 minutes during activity, an athlete should consume 5 ounces of fluid for a player weighing 90 lbs or less and 9 ounces of fluid for a player weighting more than 90 lbs. Once the activity is over, an athlete should drink water or a sports drink every 15-20 minutes for the first hour after activity.

TRAINING

Training modifications based on the WBGT include implementing mandatory match play hydration breaks during competition, limiting intensity or duration of training, and possibly delaying training until the WBGT decreases.

WARNING SIGNS

Early warning signs of dehydration and heat illness include increased fatigue, dizziness, nausea, headache, dry lips and tongue, irritability, muscle cramping, red flushed face, and dark yellow urine. If any of these occur, an athlete should be removed from play to a cooler, shaded area, given fluids to drink (water or an electrolyte-containing sports drink), and gently cooled with ice packs or cool wet towels. If the athlete does not rapidly improve or develops an altered mental status such as confusion or extreme lethargy, heat stroke (which is a medical emergency) should be assumed and EMS (911) should be called.

With proper awareness and prevention techniques, most heat-related illness can be avoided or minimized, and athletes can focus on enjoying training and competition during the heat of summer.

For more detailed information, refer to the following resources from which much of the material for this article was obtained:

• US Soccer Federation 2006 Youth Soccer Heat and Hydration Guidelines
• US Soccer Heat Guidelines

Prepared by Dr. Thomas I. Sherman

ANKLE SPRAINS
A sprain is an injury to ankle ligaments - the structures responsible for holding the ankle in the appropriate alignment. Depending on the position of the foot and the motion of the body, different ligaments may be injured. The most commonly affected ligaments are those on the outside or lateral aspect of the ankle. The typical mechanism by which these occur is rolling the ankle with the foot pointed down and inward. The severity of the ankle sprain is dictated by multiple factors, the most important of which is the energy imparted by the injury to the ankle.

• GRADE I SPRAIN
  Recovery process = 2-10 days
  

• 2ND DEGREE SPRAIN
  More severe
  Excessive abnormal motion of the ankle
  Difficulty with impact activities
  Recovery process = 10-30 days
  

• 3RD DEGREE SPRAIN
  Severe swelling
  Instability of the ankle
  Inability to bear weight
  Recovery process = 1-3 months
  Severe swelling
  Instability of the ankle
  Inability to bear weight
  Recovery process = 1-3 months
  

Regardless of the severity, the initial treatment should consist of PRICE therapy:

Protection, Rest, Ice Compression, and Elevation.
It is vital to protect the ankle from further injury by avoiding pain inducing activities. With severe sprains, immobilization of the ankle in a boot may be required. Rest is essential to allowing the ankle to heal. Ice will help decrease swelling and reduce pain. This should be done 10-20 minutes every 1.5 to 2 hours for the first 2 to 3 days. Compression and elevation help reduce swelling.

If there is difficulty bearing weight and/or significant swelling and pain, medical attention is required to ensure there is no fracture (break in the bone) by taking X-rays. Medications to decrease inflammation may be prescribed. Finally, referral to a physical therapist may be required to facilitate an expedient recovery. Focus is typically given to restoring balance and strength. Return to play is recommended when normal motion is restored, strength is regained, and impact activities are no longer painful. Consideration may be given to taping or bracing the ankle during the initial return to play period. 

Sometimes the sprained ligament does not heal property, and the ankle continues to remain unstable despite following the typical rehabilitative process. When this is the case, surgery is required. Here, the ligament is surgically repaired or reconstructed. Often, an ankle arthroscopy will be performed at the same time. This is a minimally invasive technique to treat injuries to the joint surfaces. This is performed on an outpatient basis and return to full play is typically in 3 to 4 months.

ANKLE JOINT INJURIES

These are often associated with instability of the ankle such as recurrent sprains. If left untreated, these injuries, known as osteochondral lesions of the talus or osteochondral defects, may lead to persistent pain and even progress into arthritis. These injuries will typically be associated with persistent ankle pain, particularly with impact activities. Swelling with activity, and even popping or grinding when moving the ankle are common.

These injuries are typically diagnosed by MRI. Sometimes surgery is required. This typically consists of removing the injured surface and promoting a healing response or even repairing the damaged portion of the joint surface with graft material. Seeking treatment with an orthopedic foot and ankle surgeon specialist is advisable when this type of problem is suspected.

WINTER SPORTS INJURY PREVENTION

Written by Adam Hyatt, M.D.

Many of these injuries happen at the end of the day’s activity, when people overexert themselves to finish that one last run before the day’s end. The majority of these injuries can easily be prevented if participants prepare for their sport by keeping in good physical condition, staying alert, and stopping when they are tired or in pain. Fatigue can create poor technique and loss of protective mechanisms.

There are many things you can do to help prevent injury during favorite winter activities. Winter athletes should take extra steps to incorporate specific strategies to prevent injuries. According to the American Academy of Orthopedic Surgeons these include:

• Never participate alone in a winter sport.

• Keep in shape and condition muscles before participating in winter activities.

• Warm up thoroughly before playing or participating. Cold muscles,tendons, and ligaments are vulnerable to injury.

• Wear appropriate protective gear, including goggles, helmets,gloves, and padding.

• Check that equipment is working properly prior to use.

• Wear several layers of light, loose, and water/wind-resistant clothing for warmth and protection. Layering allows you to accommodate your body’s constantly changing temperature. Wear proper footwear that provides warmth and dryness, as well as ample ankle support.

• Know and abide by all rules of the sport in which you are participating.

• Take a lesson (or several) from a qualified instructor, especially in sports like skiing and snowboarding. Learning how to fall correctly and safely can reduce the risk of injury.

• Pay attention to warnings about upcoming storms and Pay attention to warnings about upcoming storms and severe drops in temperature.

• Seek shelter and medical attention immediately if you, or anyone with you, is experiencing hypothermia or frostbite. Make sure everyone is aware of proper procedures for getting help, if injuries occur.

• Drink plenty of water before, during, and after activities.

• Avoid participating in sports when you are in pain or exhausted.

• Become familiar with your surroundings. Know the whereabouts of fences, trees, rocks, open water, and ice patches so they can be avoided. Stay on marked trails and avoid any potentially dangerous areas such as steep hills. Slippery surfaces are particularly troublesome, as they can cause sudden jarring movements (e.g., unnatural fall avoidance).

• Reduce risk of severe head injuries with protective head gear. The National Pediatric Trauma Registry reports that almost half of all winter sports injuries are head injuries. Protect children from traumatic brain injury, disability, and possible death by having them wear a properly fitted helmet when sledding, ice skating, playing hockey, skiing, snowboarding, and snowmobiling.

• Sled feet first. Sledding feet first makes sledding safer. Children should also always have adult supervision while sledding. Make sure the sled route is clear of trees and rocks.

SNOW REMOVAL AND COLD WEATHER TIPS

When you head out to shovel, make sure you dress warm and in layers. Most people end up bundling up but get hot once they start working and shed the coat. It is better to dress in layers which can help you shed piece by piece when you start to get too warm.

Early signs of cold injury (called frost nip) can occur when temperatures fall below freezing. The skin typically appears white and numb. This is best treated by moving to a warm indoor location, removing any wet clothing, and submerging the area in warm (not hot) water. Remember, dressing warm will keep your muscles warm, which will help prevent strain or unnecessary tension.

Also, make sure you wear proper footwear. Don’t head out in regular tennis shoes or dress shoes. Treaded, warm boots help support your feet and body and will give you better traction if it is icy.Another good rule of thumb is to do some stretching before you go outside to loosen your muscles and warm them up. Warm muscles work more efficiently and are less likely to be injured.

Lastly, shovel early and often. Newly fallen snow is lighter and easier to move than when it is wet and packed down. When you shovel, push the snow rather than lift it. Remember to pace yourself and take frequent breaks.

3 oz. grilled chicken, fish, or turkey 

1 C. fresh salad  (oil and vinegar dressing)

 8 oz. water or fat free milk

REVIEWED BY DR. MICHAEL W. GISH.

Since the true cause of shin splints is unknown, however, there are a few theories of how they occur. This is including (but not limited to): inflammation of the surrounding tissue of the shin bone (periosteum), tenderness or injury to the surrounding musculature or tendons (e.g. soleus, tibialis posterior, tibialis anterior), reactions to repetitive stress or high weight loads causing bending of the tibia or increased strain, traction on the periosteum by an imbalance of lower leg musculature, and decreased bone density. Some risk factors that have been linked to shin splints include:

• High body mass index
• Flat feet
•  Being a female
•  Inexperience in running 
• Previous history of shin splints
• Changing running surfaces

So now that we know the potential causes of shin splints, how can we prevent them?

Although research has not come up with a perfect prevention program for shin splints, there are a few training strategies that have promise to work. First and foremost, however, is footwear. Insuring that your feet have proper arch support, cushioning, and/or durability to withstand the forces that are being placed on your body can be a tremendous help in preventing over-use injuries. Also, the mileage and overall wear-and-tear on the footwear may be an important factor, as older shoes lose support and harmful stresses can impact the lower body leading to injury. Cleats or turf shoes may not have the best arch support. It is recommended to have your feet evaluated by a specialist as you may require insoles or custom orthotics.

Training strategies in preventing shin splints include appropriate stretching and dynamic warmup exercises. Stretches that have shown to help shin splints would be stretching the two muscles that make up that calf muscle: the gastrocnemius and soleus. All of the stretches can be completed by performing 3 sets of 30 second hold; 3-5 times per day. The gastrocnemius can be stretched by leaning up against a wall in a lunge stance, while keeping the heel of the back leg on the ground, and with the back knee straight, lean into the wall. To stretch the soleus, assume the same lunge position, but instead of keeping the back leg straight, bend at the knee and lean. The soleus is the muscle that is usually forgotten when the calf is stretched, and this can create unequal stresses on the tibia or shin bone. Another muscle to stretch may be the tibialis posterior, this muscle can get overworked at times when there is not enough arch support. This muscle can be stretched best barefoot and by sitting in a figure 4 position with the ankle resting on top of the opposite knee, next grab the inside of the heel in one hand and push the heel down towards the floor, at the same time with the other hand grab the top of the foot and push towards the floor as well, you should feel the stretch along the inside of the shin bone.

FIFA 11+ is one dynamic warmup or training program that has been measured to have a decrease in injury risk rates by 35%. Additionally, teams that have added FIFA 11+ into their training have shown to have between 30% and 70% fewer players with injuries. FIFA 11+ has training that include stabilization of the core, eccentric movements for the thigh muscles, proprioceptive exercises, and proper postural alignment with dynamic stabilization and plyometric training. The only equipment used would be a soccer ball, and the program can be completed in 10-15 minutes when athletes are properly trained with the movements. Some of the specific exercises that would prevent shin splints would be the single leg stance, squats with either toe raise, walking lunges, or one-leg squats, jumping, and running exercises.

While there is no “gold standard” in 100% prevention of shin splits, proper footwear, stretching, and a dynamic warm-up with FIFA 11+, has been shown to have positive results in preventing overuse injuries. Additionally, having adequate rest time, not over training, and training on appropriate surfaces may also help to prevent shin splints from arising. Overall, by staying in tuned with your body and preparing well for practices and completions by stretching and warming-up in a balanced fashion are appropriate ways to prevent shin splints.

PREPARED BY JESSICA YARNALL MS, LAT, ATC

References:

Barengo NC., Meneses-Echávez JF., Ramírez-Vélez R., Cohen DD., Tovar G., Bautista JE. The impact of the FIFA 11+ in football players: A systematic review. 2014;11: 11986-12000.

Bonasia DE., Rosso F., Cottino U., Rossi R. Exercise-induced leg pain. Asia-Pac J Sport Med. 2015; 2: 73-84.
Craig DI. Medial tibial stress syndrome: Evidence-based prevention. J Athl Training. 2008;43(3): 316-318.

Loudon JK., Dolphino MR. Use of foot orthoses and calf stretching for individuals with medial tibial stress syndrome. Foot Ankle Special. 2010;3(1): 15-20.

Pengel KB. Common overuse injuries in the young athlete. Pediatr Ann. 2014;43(12): 297-308.

Staying active and fit indoors can be a big challenge during the winter months, especially if you don’t have gym equipment at home. This article aims to provide you with tips for staying active and healthy indoors using every day activities and your own body movements.

Activities of Daily Living

Over time you may have heard healthcare professionals refer to ADL’s or Activities of Daily Living. ADL’s are simply activities one commonly does over the course of day to day life. Examples of some common indoor ADL’s are washing dishes, doing laundry, or dusting the house just to name a few. If you are looking for easy ways to improve your fitness indoors without gym equipment, changing the way you approach your ADL’s can make a positive impact on your health.  Try doing housework at a pace that increases your heart rate and makes you feel like you are getting a workout. This will help burn more calories and improve your cardiovascular fitness while you get work done.

Using ADL’s To Improve Fitness

·         Increase the pace with which you perform the activities – doing this will force your body to work harder, therefore increasing your heart rate and burning more calories.

Make the most of TV time

Many people spend some part of every day in front of the TV, but this time is great for more than just watching the news. While watching your favorite program try doing some simple exercises that can give your body a great workout. Pushups, sit-ups, squats, lunges, and jumping jacks can all be performed in front of the TV. All of these exercises can be performed by healthy individuals of any age. If you have any questions it is best to check with a physician before starting new exercise.

Simple Exercises for TV Time

·         Push-ups

·         Sit-ups

·         Jumping Jacks

·         Lunges

·         Squats

Take the stairs

If you have a staircase in your home, use it to maximize your fitness. Walking or running up and down the stairs is a great way to work the lower body and the cardiovascular system at home.  Stairs can also be used for variation on different exercises, such as incline push-ups. Be careful and use good judgement when using stairs to exercise.

Simple Exercises Involving the Stairs

·         Walk up and down

·         Run up and down

·         Incline Push-ups

·         Calf raises

Conclusion

When you are inside at home with no gym equipment, finding ways to exercise can be a challenge. Using your creativity and finding ways to turn your home into a gym is another powerful tool you can add for increased fitness. Using your imagination and this article can guide you in the right direction towards getting fit at home without gym equipment.

Most people do not realize how important posture is.  If you don't correct it, poor posture tends to keep getting worse as your body tries to compensate for it.  Poor posture also causes strain on the body and leads to weakening of the postural muscles, particularly given the amount of time we now spend sitting for our jobs and relaxation.  Poor posture can cause injuries like back/neck/shoulder pain, TMJ and even headaches.

Correcting posture requires retraining your brain to remember years of a “bad habit”, however it is worth it considering it will lead to less pain/injuries:

• Awareness of your posture- straighten your back, lift your chest, roll your shoulders back and rotate your pelvis so your stomach and behind are tucking in – have all 3 curves in your spine
• Take Breaks!!! Even if it is only 30 seconds – sit no more than 30 minutes!
• Chair/Table set up: feet supported with no crossed legs with hip/knees at 90 degree angle and even weight between hips
• Sit back in the chair so your buttock is touching the back rest and the back of the knee should be about an inch from the edge, potentially a small rolled up towel in your lower back,
• Arms/Forearms Supported:  Rest your elbows/arm on your chair or desk or pillows keeping shoulders relaxed. 
• Screen height should be eye level and close to you- potentially use books to stack screen up so you don’t have to move your head
• Avoid rotating/twisting at the spine, keep objects close to you and rotate body as a whole