There is little data on the long-term outcome of rotating hinge total knee arthroplasty. We provide a clinical and radiographic assessment of survivorship of the Kinematic rotating hinge total knee arthroplasty (How-medica, Rutherford, NJ), in a series of 72 implants, performed by a single surgeon in one unit, between 1983 and 1997. Survival analysis using known all cause revision revealed a 92% five-year implant survival, but worst-case scenario was 31% at five years.

In a subset of 27 patients we used the Nottingham Health Profile (NHP) to assess prospectively the changes in health-related quality of life following rotating hinge arthroplasty. In this salvage arthroplasty setting we demonstrate a significant improvement in two modalities of the NHP (pain and physical mobility).

Purpose: To study the functional outcome and survivorship of custom designed knee implants for revision and primary total knee replacement surgery where off-the-shelf prosthesis were unsuitable.

Methods: We prospectively reviewed the clinical and radiological results of 20 patients with 23 custom designed total knee prosthesis from 1991 to 2000. The indications were bone loss due to multiple revisions of total knee prosthesis and debridement for infection; peri-prosthetic fractures; bone deformity with rickets and small bones of patients with juvenile chronic arthritis. All the patients had their knee designed and manufactured in the Centre for Biomedical Engineering, University College London Medical School, Stanmore, UK. There were 4 different designs of knee prosthesis used: Condylar knee of miniature size, CAD-CAM knee, Superstabiliser and Rotating Hinges. Patients were operated upon by one senior surgeon and the Hospital for Special Surgery score taken pre-operatively, at three months, and yearly by an independent research physiotherapist.

Results: Clinical and radiological results after an average of 62.5 months (range 22 to 118 months) showed that the average Hospital for Special Surgery Score improved significantly (p=0.025) from 13.5 points (range 0–48) pre-operatively to 86.5 points (range 62–96 points). Average maximum flexion post operatively measured 86.4 degrees (range 60–122 degrees). 16 knees had excellent, 5 good and 2 poor results. Three patients had an extension lag ranging from 15–25 degrees. Only one patient with juvenile chronic arthritis needed revision at five years after the index arthroplasty.

Conclusion: The clinical and radiological results compare favorably with those who had standard knee prosthesis with similar indications. Our results support the use of a custom designed knee implant as a salvage prosthesis and an alternative to arthrodesis or amputation.

Purpose: To study the effect of retaining an abraded femoral component on the outcome of primary revision of uncemented total knee prosthesis.

Method: 66 revision procedures for failed uncemented porous coated anatomic (PCA) total knee replacement were performed in 60 patients. At review, four patients had died while two were lost to follow up, therefore 60 knees in 54 patients were included in this prospective study. The principal indications for primary revision were polyethylene wear and loosening of the tibial base plate. 14 patients had a well fixed femoral component and hence were retained while 46 patients had both the components revised. All patients were prospectively assessed prior to surgery, at three months, six months and yearly thereafter. Review comprised clinical and radiological assessment. The mean follow up was 8.4 yrs (7–12 yrs)

Summary of results: The mean pre-operative Hospital for Special Surgery knee score after the first revision improved at a follow up of 8.4yr (7–12yr) giving 39 (65%) excellent, 17 (28.4%) good and four (6.6%) poor results. 13 out of 60 knees needed a further revision. Six of these second revisions which had only the tibial component changed failed very early (mean of 2.1 yr) when compared to the rest (6.8yr), probably due to wear between the abraded retained femoral component and polyethylene insert. The estimated odds ratio (relative risk) of second revision in patients with retained femoral component compared to those with revision of both the components was 4.17 (95% C.I. 1.07 – 15.4).

Conclusion: We recommend exchange of all the components at the time of revision of PCA knee prostheses. Significance: To our knowledge, this is the only study involving such a large number of PCA revisions and looking into the effect of retaining the femoral component compared to changing both the components on the outcome of revision.

Aim: To prospectively determine the functional outcome of revision total knee replacement (TKR).

Method: We carried out a prospective outcome study recruiting 65 consecutive revision total knee replacements carried out by the senior author between 1992 and 1995. The indications for revision were aseptic loosening in 40 cases, instability in 7, infection in 4, and 16 cases for other causes. All patient was assessed preoperatively and at 3 and 12 months postop using the Nottingham Health Profile (NHP) to measure general health status. As part of this ongoing study, followup data is available for 24 patient at 5 years.

Results: There were 65 revisions in 60 patients, 5 being bilateral. There were 37 females and 23 males, with a mean age of 63 years (range 29 to 86 years). The preoperative scores showed that the patient had significant disability related to their failed TKR. Three months postop, there was a significant improvement in the NHP scores for pain and social isolation. At 12 months, the level of pain was again significantly improved over the 3 month score.

At 5 years, the pain score for the revision group deteriorated but remained better than the baseline level. This is in contrast to post primary TKR, where the improvement in pain score was maintained from 3 months onwards.

Conclusion: This study shows a significant improvement in the level of pain following revision knee arthroplasty. However, patients remain significantly disabled afterwards and do not show the very marked improvement in general health seen after primary TKR.

Aim: To determine the quality of life and radiological outcome of the rotating hinge total knee prosthesis as a salvage procedure for failed knee arthroplasty.

Methods: Forty-seven consecutive revision total knee arthroplasties, using the rotating hinge component, implanted between November 1983 and June 1997, were studied. The principal indications for surgery were pain with ligamentous laxity and gross bone loss. There were 43 patients, 11 males, 32 females, 19 left and 28 right, 21 with rheumatoid disease and 22 with osteoarthritis. The mean age at revision was 68 years, mean time from primary procedure to revision of 8 years and a mean number of previous knee procedures of 1.6 (range 1–5). The average time to final follow-up was 5 years. Quality of life was determined using the Nottingham Health Profile (NHP) combined with standard clinical and radiological assessment.

Results: Of the 47 revision procedures, full clinical follow-up information was available on 43 (91.5%), radiographic follow-up on 38 (80.9%). Complications occurred in 10 out of the 47 arthroplasties (21.3%) including 4 deep infections, 2 femoral fractures, 2 patients with clinically apparent aseptic loosening and 2 significant extensor mechanism problems. Survivorship analysis revealed a 5year cumulative implant survival of 89%. Significant improvements in quality of life (pain and physical mobility) were shown at 12 months post-operatively.

Discussion: This is a prospectively-studied series of salvage arthroplasty procedures. We regard quality of life as a key indicator of surgical success after knee arthroplasty. Rotating hinge arthroplasty offers objective and reproducible improvement in quality of life for failed knee arthroplasty with ligamentous instability.