I would like to commend this article by Brown et al.; it is well written, well documented, and realistic in its analysis of extensor tendon allografts, which have become the final common pathway for extensor mechanism ruptures after total knee replacement. Although Brown et al. suggest that enthusiasm for this procedure, no matter how desperate the situation, should be modest or guarded, their data are irrefutable and consistent with my own experience of almost 250 extensor tendon allografts over the past twenty years. There is no question that the explosion of joint replacement, particularly in younger patients, will create the need for more and definitely better alternatives to this problem.

After the initial identification of an extensor mechanism rupture and the angst that every surgeon feels at that moment, it is important to try to ascertain the cause. Early ruptures are frequently due to compromised replacements that are either unstable or stiff after index total knee arthroplasty. My own experience, as well as that of the authors, is that almost 50% of these patients will need a simultaneous knee revision as well as an extensor allograft reconstruction. Many of these individuals have an infection and are undergoing the same procedure (often after an antibiotic spacer block), and they are at even greater risk for long-term infection and failure. These ruptures usually occur fairly early in the recuperative period, whereas extensor ruptures from falls or attenuation of the tendon from disease processes such as rheumatoid arthritis may present years later. The surgeon must be ready to perform a revision, probably to a constrained condylar knee or hinged device with stems to protect the subsequent and often simultaneous allograft.

Almost all surgeons faced with a primary extensor mechanism rupture will attempt a primary repair. However, for several decades, the literature has shown the results of this approach to have been largely ineffectual, often with success rates of only ≤10%. Achilles tendon allografts, iliotibial-band or semitendinosus grafts, and the newest synthetic mesh techniques all have substantial early and late failure rates. Bracing is rarely tolerated for any length of time by patients, who often think that they may be better off with a fusion or an amputation. The authors’ 4% amputation rate is certainly in keeping with that of the general experience in the orthopaedic community.

As a certain percentage of these extensor mechanism ruptures are related to or are difficult to distinguish from infected knees, this potential problem must be examined with all of the available technology: erythrocyte sedimentation rate, C-reactive protein, bone scan, and alpha-defensin levels, if they are available. To perform a primary exchange in an infected arthroplasty with the supplemental use of the nonviable allograft tissue is only to invite persistent deep infection.