A review of US Army service members following hip arthroplasty found 183 over a six year period. Two years after surgery, 44 (24%) were medically discharged, 82 (45%) retired and 57 (31%) returned to active duty. Officer rank had an OR of 3.63 for postoperative combat deployment compared to enlisted rank (Jorgensen et al., 2013).
A comparison between metal on metal, and metal on plastic total hip arthroplasty found no significant differences in wear rates. Cobalt and chromium concentrations were elevated after MOM-THA but there was no significant differences in complication rates in short to mid-term follow up (Qu et al., 2011). Longer follow-up may be needed to show the expected advantage in wear rates.
Ceramic on ceramic total hip replacements have shown excellent clinical results, but a significant side effect is 'squeaking' which appears to be a problem with metal-on-metal bearings too. One study found 14 (10.4%) of 131 patients complaining of squeaking although only one patient had complained prior to the study and squeaking was only reproducible in four cases (Jarrett et al., 2009). Survival of COC-THA have been recorded as 90.8% to 97.4% at ten years in young and active patients (Hannouche et al., 2011).
A systematic review found excellent results from COC-THA with exceptionally low wear rates and virtually no local adverse effects. The main concerns were insertional chipping, in-vivo fracture and squeaking. Metal-on-metal second generation stemmed prosthetics reported a mean survival of 96-100% at 38-60 months, while resurfacing studies reported 94-98% mean survival at 33 months. Ceramic-on-ceramic studies reported 100% survival at 51 months and 96% at 8 years. It was felt likely that the use of hard-on-hard bearings will continue to increase, especially in young and active patients (Zywiel et al., 2011).
Significant problems have been noted with the extra-large diameter MOM DePuy ASR XL prosthesis, with a total of 28.6% showing implant dysfunction including pain, loosening, squeaking and grinding. 17.1% required revision(Bernthal et al., 2012).
Firefighters have been able to return to operational duties after hip replacement. An internet response among Fire Service Medical Advisers in 2003 identified ten firefighters who had recently undergone total hip replacement; 7 had reached retirement age and left, or left early on ill-health retirement while the 3 remaining had yet to serve five years post-surgery. Of five hip resurfacing operations (Birmingham) four were still serving within five years of surgery (Williams, 2003).
Hip arthroplasty in the young has less favourable results. A follow-up of 63 cases aged less than 20 at surgery with cemented polyethylene acetabular cups found the probability of failure (loosening or revision) reached 45% after fifteen years. Higher risk of failure was associated with more than one previous procedure involving the hip, unilateral arthroplasty, previous hip trauma, and a higher level of postoperative physical activity. The conclusion was that total hip arthroplasty in adolescents should be reserved for carefully selected patients, and fixation of the acetabular component with cement was not recommended (Torchia et al., 1996).
Some studies have showed increased failure rates among those doing high levels of activity, particularly high impact sports, while others show that physical activity promotes bone strengthening and argue that the positive benefits of activity outweigh the effects of wear. A general consensus has identified three groups of activity, those that are recommended, those allowed with experience and those not recommended. It is argued that an experienced athlete has sufficient proprioceptive control to minimise stresses on joints, while the newcomer may have higher risk of sudden stresses. A good example is skiing, where the inexperienced skier will have an unstable position with frequent falls while the experienced skier will adopt a stable position with good control. A full list of sporting activities was developed following the 1999 American Hip Society Survey. This is available in free-text online publications (Golant et al., 2010). The list includes cross-country skiing and horseback riding for those with experience, but does not recommend rock climbing, football, jogging, and racquet sports.
Many military and most police and firefighting activities are compatible with a total hip arthroplasty, and even those involving strenuous activity should not compromise the joint significantly. High impact activities such as parachuting would probably be an exception. Firefighters or police with a total hip replacement are not likely to be harmed by full operational employment. The key issue is whether they are capable of undertaking their role, and particularly whether they can maintain fitness. The evidence shows that many have successfully done so.
Significantly lower survival rates have been recorded for cemented implants compared to cementless implants after an average 20 year follow-up (Corten et al., 2011). This is not, however, supported by wider literature reviews which suggest the most reliable results are achieved with cemented implants in patients under 50 years old (De Kam et al., 2011).
Choice of fixation for the acetabular component does appear to be more important in younger, more athletic individuals, with a greater risk of failure of cemented acetabular component compared with the press-fit components (Golant et al., 2010).
There is a risk of posterior dislocation following hip replacement surgery. This is greater where the posterior approach is used as this involves detaching the posterior hip rotator muscles. Using the anterior approach preserves the muscles which stabilise the hip and allows more freedom in postoperative rehabilitation with a faster recovery (Berger et al., 2004). Capsular repair during posterior approach substantially reduces the risk of dislocation. Anterolateral and lateral approaches can require detachment of the hip abductors via a trochanteric osteotomy, leading to temporary or permanent abductor weakness, and abduction exercises should be avoided initially after surgery. Revision hip surgery can involve significantly more invasive procedures to access the joint (Golant et al., 2010).
In the first six weeks following surgery, patients are generally advised to avoid flexing beyond 90 degrees (use elevated toilet seats and chairs) and rotating more than 45 degrees internally or externally. Adduction should be avoided, and at night a pillow should be placed between the thighs. In a study comparing patients advised on these restrictions and patients who were unrestricted, the average time to return to work was 6.5 weeks in the unrestricted group and 9.5 weeks in the restricted group. All 98 patients in the unrestricted group had returned to their normal occupation within six months while only 81 out of 85 had done so from the restricted group (Peak et al., 2005). There is little in the literature on returning to work after THA, and the time to return varies substantially from a little over a week to several months, although most returned swiftly. Operative technique may be relevant, but as in many studies of returning to work after surgery, advice from doctors seems to hinder rather than help their speed of return (Kuijer et al., 2009).
Cemented prostheses can weight-bear immediately after surgery, while cementless prostheses need a period of partial weight-bearing, usually six weeks, to allow bone ingrowth.
Patients who undertook maximal strength training with leg press and abduction five times a week for four weeks improved strength, rate of force development and improved work efficiency. Work efficiency was improved at six months by 29% and at twelve months by 30% in those who added strength training to conventional rehabilitation. Improvement in leg press performance was increased by 36% and 74% respectively (Husby et al., 2009, Husby et al., 2010). Early multidisciplinary rehabilitation can improve outcomes but there is little long-term evidence available (Khan et al., 2008).
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WILLIAMS, A. N. December 2013 2003. RE: Return to firefighting after hip arthroplasty - internet forum response.
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