https://www.thelancet.com/pdfs/journals/lancet/PIIS0140673607604577.pdf

The operation of the century: total hip replacement

Forty Oxford medial unicompartmental arthroplasties (UCAs) were performed through a short incision medial to the patellar tendon, without dislocation of the patella, using updated instruments (Oxford Knee Phase III, Biomet Ltd., Bridgend, UK). The rate of recovery of these knees (measured by the time taken to achieve straight-leg raising, 70° of flexion, and independent stair climbing) was compared with that of 20 Oxford UCAs performed through an open approach with dislocation of the patella. Both groups were compared with 40 AGC (Biomet) total knee arthroplasties performed for osteoarthritis during the same time period. The average rate of recovery after the short-incision UCA was twice as fast as after open UCA and 3 times as fast as after total knee arthroplasty. Accuracy of implantation, assessed from 11 variables seen on fluoroscopically centered postoperative radiographs, was the same after UCA by the short-incision approach as after the open approach, suggesting that the short-term advantage of increased speed of recovery was gained without affecting the long-term results. We now employ the short incision with the phase III instruments for all UCAs.

Rapid recovery after oxford unicompartmental arthroplasty through a short incision.

We describe the outcome of a series of 124 Oxford meniscal-bearing unicompartmental arthroplasties carried out for osteoarthritis of the medial compartment. They had been undertaken more than ten years ago in a non-teaching hospital in Sweden by three surgeons. All the knees had an intact anterior cruciate ligament, a correctable varus deformity and full-thickness cartilage in the lateral compartment. Thirty-seven patients had died; the mean time since operation for the remainder was 12.5 years (10.1 to 15.6). Using the endpoint of revision for any cause, the outcome for every knee was established. Six had been revised (4.8%). At ten years there were 94 knees still at risk and the cumulative survival rate was 95.0% (95% confidence interval 90.8 to 99.3). This figure is similar to that reported by the designers of the prosthesis and to the best published results for independent series of total knee replacement. If patients are selected appropriately, this implant is a reliable treatment for anteromedial osteoarthritis of the knee.

Oxford medial unicompartmental knee arthroplasty. A survival analysis of an independent series.

Between 1989 and 1992 we had 102 knees suitable for unicompartmental knee replacement (UKR). They were randomised to receive either a St Georg Sled UKR or a Kinematic modular total knee replacement (TKR). The early results demonstrated that the UKR group had less complications and more rapid rehabilitation than the TKR group. At five years there were an equal number of failures in the two groups but the UKR group had more excellent results and a greater range of movement. The cases were reviewed by a research nurse at 8, 10 and 12 years after operation. We report the outcome at 15 years follow-up. A total of 43 patients (45 knees) died with their prosthetic knees intact. Throughout the review period the Bristol knee scores of the UKR group have been better and at 15 years 15 (71.4%) of the surviving UKRs and 10 (52.6%) of the surviving TKRs had achieved an excellent score. The 15 years survivorship rate based on revision or failure for any reason was 24 (89.8%) for UKR and 19 (78.7%) for TKR. During the 15 years of the review four UKRs and six TKRs failed. The better early results with UKR are maintained at 15 years with no greater failure rate. The median Bristol knee score of the UKR group was 91.1 at five years and 92 at 15 years, suggesting little functional deterioration in either the prosthesis or the remainder of the joint. These results justify the increased use of UKR.

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Unicompartmental or total knee replacement: the 15-year results of a prospective randomised controlled trial.

Background Unicompartmental arthroplasty is a treatment alternative when only one compartment of the knee is affected with arthritis, but the reported results of this procedure have been variable The purpose of the present study was to evaluate the results of a modern unicompartmental knee arthroplasty performed with use of a cemented metal-backed prosthesis and surgical instrumentation comparable with that used for total knee replacement Methods The indications for the procedure were osteonecrosis or osteoarthritis associated with full-thickness loss of cartilage that was limited to one tibiofemoral compartment as evaluated on standing and stress radiographs One hundred and sixty consecutive cemented metal-backed Miller-Galante prostheses in 147 patients were evaluated after a mean duration of follow-up of sixty-six months (range, thirty-six to 112 months) The mean age of the patients at the time of the index procedure was sixty-six years Results Three knees were revised because of progression of osteoarthritis in the patellofemoral joint (two knees) or the lateral tibiofemoral compartment (one knee) Two knees had revision of the polyethylene liner The average Hospital for Special Surgery knee score improved from 59 points preoperatively to 96 points at the time of the review According to Kaplan-Meier analysis, the ten-year survival rate (with twenty-nine knees at risk) was 94% +/- 3% with revision for any reason or radiographic loosening as the end point Conclusions A modern unicompartmental knee arthroplasty is a valid alternative for patients with unicompartmental tibiofemoral noninflammatory disease The patient selection must be strict with regard to the status of the patellofemoral joint The preoperative planning includes stress radiographs to assess the correction of the deformity and the status of the uninvolved compartment Continued long-term follow-up is necessary to evaluate long-term polyethylene wear

Modern unicompartmental knee arthroplasty with cement: a three to ten-year follow-up study.

Many designs of unicompartmental knee replacement show early and mid-term failure due to polyethylene wear. We studied the wear rate of congruent polyethylene meniscal bearings retrieved from failed Oxford unicompartmental knee replacements. We examined 16 bearings, 0.8 to 12.8 years after implantation, measuring their thickness and comparing it with that of 14 unused bearings. The mean rate of penetration, which included the effects of wear at both upper and lower surfaces, was 0.036 mm per year (maximum 0.08). Bearings as thin as 3.5 mm wore no faster than thicker models, but ten with evidence of impingement had greater wear. The six bearings with no impingement showed a mean rate of penetration of 0.01 mm per year. In unicompartmental knee replacement, careful implantation of fully congruous meniscal bearings can avoid failure due to polyethylene wear.

Wear of congruent meniscal bearings in unicompartmental knee arthroplasty: A RETRIEVAL STUDY OF 16 SPECIMENS

We determined the outcome of 56 'Oxford' unicompartmental replacements performed for anteromedial osteoarthritis of the knee between 1982 and 1987. Of these, 24 were in patients who had died without revision, one was lost to follow-up and two had been revised. Of the remaining 29 knees, 26 were examined clinically and radiologically, two were only examined clinically and one patient was contacted by telephone. The mean age of the patients was 80.3 years. At a mean follow-up of 11.4 years (10 to 14) the measurements of the knee score, range of movement and degree of deformity were not significantly different from those made one to two years after operation, except that the range of flexion had improved. Comparison of fluoroscopically-controlled radiographs at a similar interval of time showed no change in the appearance of the lateral compartments. The retained articular cartilage continued to function for ten or more years which suggests that anteromedial osteoarthritis may be considered as a focal disorder of the knee. This justifies continued efforts to develop methods of treatment which preserve intact joint structures.

Does arthritis progress in the retained compartments after 'Oxford' medial unicompartmental arthroplasty? A CLINICAL AND RADIOLOGICAL STUDY WITH A MINIMUM TEN-YEAR FOLLOW-UP

Many designs of unicompartmental knee replacement show early and mid-term failure due to polyethylene wear. We studied the wear rate of congruent polyethylene meniscal bearings retrieved from failed Oxford unicompartmental knee replacements.We examined 16 bearings, 0.8 to 12.8 years after implantation, measuring their thickness and comparing it with that of 14 unused bearings. The mean rate of penetration, which included the effects of wear at both upper and lower surfaces, was 0.036 mm per year (maximum 0.08). Bearings as thin as 3.5 mm wore no faster than thicker models, but ten with evidence of impingement had greater wear. The six bearings with no impingement showed a mean rate of penetration of 0.01 mm per year.In unicompartmental knee replacement, careful implantation of fully congruous meniscal bearings can avoid failure due to polyethylene wear.

http://www.researchgate.net/profile/Ross_Crawford/publication/13433271_Wear_of_congruent_meniscal_bearings_in_unicompartmental_knee_arthroplasty._A_retrieval_study_of_16_specimens/links/004635321fbffd779a000000.pdf

Wear of congruent meniscal bearings in unicompartmental knee arthroplasty

We determined the outcome of 56 ‘Oxford’ unicompartmental replacements performed for anteromedial osteoarthritis of the knee between 1982 and 1987. Of these, 24 were in patients who had died without revision, one was lost to follow-up and two had been revised. Of the remaining 29 knees, 26 were examined clinically and radiologically, two were only examined clinically and one patient was contacted by telephone. The mean age of the patients was 80.3 years.

At a mean follow-up of 11.4 years (10 to 14) the measurements of the knee score, range of movement and degree of deformity were not significantly different from those made one to two years after operation, except that the range of flexion had improved. Comparison of fluoroscopically-controlled radiographs at a similar interval of time showed no change in the appearance of the lateral compartments. The retained articular cartilage continued to function for ten or more years which suggests that anteromedial osteoarthritis may be considered as a focal disorder of the knee. This justifies continued efforts to develop methods of treatment which preserve intact joint structures.

Does arthritis progress in the retained compartments after ‘Oxford’ medial unicompartmental arthroplasty?

The influence of operative technique on the formation of incomplete cement mantles in the sagittal plane has been rarely considered in the literature. In this article, we discuss the influence of the anatomy of the proximal femur on the formation of incomplete cement mantles and discuss how their incidence can be reduced by correct component positioning.

V. Psychoyios

Papers

Wear of congruent meniscal bearings in unicompartmental knee arthroplasty: A RETRIEVAL STUDY OF 16 SPECIMENS

Does arthritis progress in the retained compartments after 'Oxford' medial unicompartmental arthroplasty? A CLINICAL AND RADIOLOGICAL STUDY WITH A MINIMUM TEN-YEAR FOLLOW-UP

Wear of congruent meniscal bearings in unicompartmental knee arthroplasty

Does arthritis progress in the retained compartments after ‘Oxford’ medial unicompartmental arthroplasty?

Incomplete cement mantles in the sagittal femoral plane: An anatomical explanation