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.

We report a prospective case-controlled study which compared the outcome of knee replacement in seriously deformed and slightly deformed knees. There were 51 knees with varus or valgus deformity greater than 20 degrees matched for age, gender, disease, type of prosthesis and time of operation with a control group in which the alignment of the leg was within 5 degrees of normal. The clinical outcome at a mean 5.5 years was similar in the two groups. Some deformity persisted in 14 patients in the first group, 13 of whom were initially in valgus. These patients had a significantly poorer mean clinical outcome. Lateral dislocation or subluxation of the patella was found in four knees, all of which had had valgus deformity of 30 degrees or more.

We studied the mechanical properties of cartilage from the apparently unaffected compartment of knees with unicompartmental osteoarthritis (OA). Plugs of cartilage and subchondral bone, 8 mm in diameter, were obtained from the tibial plateau of seven patients treated by total knee replacement. Control specimens were obtained from eight cadaver knees of similar age. Specimens were loaded by a plane-ended indentor in a hydraulic materials testing machine; we measured thickness, 'softness', rate of creep, and compressive strength of the articular cartilage. We found that the 'unaffected' cartilage from OA knees was significantly thinner and softer than control cartilage, and it was slightly, although not significantly, weaker. We conclude that the apparently unaffected cartilage in knees with unicompartmental OA is mechanically inferior to normal cartilage, even although clinically, radiologically and morphologically it appears to be sound.

Diaphyseal fractures of the tibia in 80 patients were treated by external skeletal fixation using a unilateral frame, either in a fixed mode or in a mode which allowed the application of a small amount of predominantly axial micromovement. Patients were allocated to each regime by random selection. Fracture healing was assessed clinically, radiologically and by measurement of the mechanical stiffness of the fracture. Both clinical and mechanical healing were enhanced in the group subjected to micromovement, compared to those treated with frames in a fixed mode possessing an overall stiffness similar to that of others in common clinical use. The differences in healing time were statistically significant and independently related to the treatment method. There was no difference in complication rates between treatment groups.

We have reviewed the results of treating 75 fractures of the proximal femoral shaft in the presence of a cemented femoral prosthesis. A simple radiographic classification into four types is proposed, and suggestions are made on the appropriate management of each. Comminuted fractures around the implant need early revision, whilst spiral fractures in this region may be treated conservatively or by operation. Transverse fractures at the level of the tip of the prosthesis are difficult to manage, and may require open reduction and internal fixation.

Antibiotic levels in bone and fat were measured in patients undergoing knee replacement to determine the time that should elapse between intravenous injection and tourniquet inflation. The tissue levels increased progressively with time, and there was wide variation in absorption rate between patients and between the two cephalosporins assessed. Five minutes should probably be left between systemic injection and inflation of the tourniquet, though two minutes may be long enough for drugs which are rapidly absorbed.

This paper reports the results of bone scans on 78 painful feet. Scanning helped in the diagnosis of persistent foot pain following injury and it enabled stress fractures, fractures of the sesamoids and subtalar arthritis to be diagnosed earlier. It reliably excluded bone infection and was useful as a screening test when radiographs were normal.

We have made a retrospective comparison between the results of 49 high tibial osteotomies and 42 unicompartmental replacement arthroplasties performed for the treatment of osteoarthritis of the knee, assessed 5 to 10 years after operation. The type of operation depended on the policy of the consultant responsible for treatment but analysis of the pre-operative findings showed that the two groups were sufficiently similar for direct comparison between them. In the replacement group, 32 (76%) were good, 4 were fair, 3 were poor and 3 had been revised. In the osteotomy group 21 (43%) were good, 11 were fair, 7 were poor and 10 had been revised. It was concluded that, in this series, the results of unicompartmental replacement were significantly better and that this group had shown no sign of late deterioration.

Five elderly patients with chronic pyrophosphate arthropathy developed stress fractures of the tibia. All patients had deformed, painful knees with the result that their increasing symptoms were not readily attributed to a stress fracture. Such a possibility should be considered in patients with chronic pyrophosphate arthropathy since early recognition makes management of the stress fracture easier.

Six different conditions of non-infective bone and joint pathology have been seen amongst 67 patients with diabetic neuropathy. The characteristics of each are described. Not all the conditions require treatment but they should be differentiated from osteomyelitis. Charcot osteoarthropathy is the most common condition seen but spontaneous fractures and dislocations generally present greater therapeutic problems. The aim of treatment should be to obtain a stable foot in which there is no undue pressure on the skin from a bony prominence.

The clinical details of six patients who developed spontaneous dislocations in the foot or ankle are presented. All were shown to have diabetic neuropathy. This previously unreported condition can occur with a short history of diabetes. Some cases can be managed without operation, though arthrodesis probably offers the best chance of obtaining a stable foot of satisfactory shape.