To the Editor:

We have read Dr. Miller's letter of June 22, 2004 and appreciate her interest concerning our review article, “Arthrodesis of the Knee”.

Our conclusion that knee arthrodesis is a functionally acceptable salvage procedure is based not only upon Harris’ data on energy expenditure (1), but an entire body of literature cited in our article documenting the poor results from resection arthroplasty and above-the- knee amputation. Most patients receiving resection arthroplasty or above- the-knee amputation were non-ambulators, when compared to the greater majority of patients receiving a knee fusion who continued to be ambulators. Many patients when faced with a choice of a knee arthrodesis or an amputation, will choose an arthrodesis because of the disagreeable thought of losing their limb. Furthermore, they understand that an amputation can be performed as a last resort if the knee arthrodesis fails or does not produce the desired clinical result.

Sierra and co-workers (2), recently published a series examining the function of twenty-five patients with above-the-knee amputations performed for failed total knee arthroplasty. Only nine of the patients were fitted with a prosthesis and only five resumed walking to a limited degree. Their conclusion was that the functional outcome following above-the-knee amputation was poor. Our review cites multiple studies documenting the function of knee arthrodesis (the original paper references #15, 21, 31, 41, 44, 58, 61, 103, 104). The majority of patients in all of these studies were able to ambulate following a knee fusion. In our experience, the literature has demonstrated that the older patient population already has balance and proprioception deficits. To have an amputation and lose this proprioceptive information from a sensate foot is severely debilitating. No modern prosthetic device can compensate for this loss. We agree with her comments that a knee arthrodesis can cause ipsilateral back pain, as well as hip pain, which has been reported (3). In that study, eighteen of forty-one patients complained of back pain as a late complication and six patients developed hip arthritis. We also agree with her comments, which were mentioned in our review, that patients with knee arthrodesis have difficulties with activities of daily living such as sitting in a movie theatre or with airline seating. However, there are many accommodative devices available to help patients with various activities of daily living tasks such as toileting and donning socks.

We agree that the conversion of a knee arthrodesis to a total knee arthroplasty is technically challenging and should not be taken lightly. In most studies, this approach has been condemned. The authors of this review currently perform take down knee fusions with the use of various adjunctive procedures including Judet quadricepsplasty (original review reference #119). It still remains to be seen whether the complication rate for these take down procedures justifies their use. Dr Millers's comments concerning this difficult procedure have been addressed by us in the penultimate paragraph of the review.

We attempted to present a concise, as well as complete eleven-page review article concerning knee arthrodesis. The more obvious disabilities with respect to knee fusion function may not have been weighted as heavily in this review. We believe that a specific report aimed at clarifying the social, functional and emotional ramifications of a knee arthrodesis certainly would be worthy of an independent research effort.

We thank you for your interest in our review.

References: 1. Harris CM, Froehlich J. Knee fusion with intramedullary rods for failed total knee arthroplasty. Clin Orthop. 1985;197:209-16.

2. Sierra RJ, Trousdale RT, Pagnano MW. Above-the-knee amputation after a total knee replacement: prevalence, etiology and functional outcome. J Bone Joint Surg Am. 2003;85:1000-4.

3. Siller TN, Hadjipaviou A. Knee arthrodesis: long-term results. Can J. Surg. 1976;19:217-9.

To the Editor:

After reading the Current Concepts Review, "Arthrodesis of the Knee", I feel compelled to comment on the authors' conclusions.

The summation of the article suggests that arthrodesis of the knee is a functionally acceptable salvage procedure for patients with failed total knee arthroplasty secondary to infection or massive bone loss secondary to tumor resection about the knee. To rely upon energy expenditure as the primary criterion to compare knee arthrodesis to above-the- knee amputations, and citing Harris, et al. who compared patients with a knee arthrodesis with those with a constrained total knee arthroplasty and those with an above-the-knee amputation, is both an incomplete and imperfect analysis.

While patients with a knee arthrodesis may have no pain at the fusion site, at short ambulatory distances they experience ipsilateral back and hip pain due to a lurching gait pattern. An assessment of patient satisfaction with surgical results must also include the difficulties associated with activities of daily living, beyond gait, which include the normally independent acts of tying shoes, donning pants and socks, getting up from a chair and toilet without assistance, traveling on an airplane, sitting in the back seat of a taxi, walking on unlevel ground, or simply climbing into a bathtub.

While conversion of a knee arthrodesis to total knee arthroplasty is fraught with technical risk, success is achievable with correct patient selection and surgical expertise. For example, in order to restore quadriceps function, a Judet quadricepsplasty and reconstruction of the patella/infrapatellar mechanism with a Finn gastroc-soleus rotationplasty, may achieve necessary functional improvement.

Furthermore, with the present state of modern prosthetics, above knee amputees require much less energy for ambulation. Previously published studies comparing above-the-knee amputees to patients with knee fusions are now obsolete. Energy efficient carbon fiber spring loaded prostheses reduce patient energy expenditure by maximizing ground reaction forces which are utilized in stepoff. Additionally, for patients with resection arthroplasties, drop lock braces provide stability during gait, but when removed, allow patients to perform activities requiring a bent knee, such as sitting at a table.

While the review article addresses most of the mechanical and technical issues surrounding knee arthrodesis, the authors should more seriously have considered its social, functional, and emotional ramifications.