This is a study of the quality of outcome of the first 100 patients who received the Twin Peg Oxford Partial knee replacement; which has been designed with a 15 degree extra surface for contact in deep flexion, and two pins for more secure fixation. We measured the outcome in patients with anteromedial osteoarthritis at 2 years after implantation using patient perception outcome measures: the OKS (Oxford Knee Score) and a patient satisfaction questionnaire. We also measured range of motion, the AKS (American Knee Society Score-Objective), the AFS (American Knee Society Score-Functional), and carried out a radiological assessment.

The results showed a mean OKS of 41, a mean AKS of 93, a mean AFS of 84, a mean range of motion of 130 degrees and a 97% satisfaction rate. Results were significantly better in male patients. There were no deaths, infections, dislocations, fractures or revisions. There were no radiolucent lines of 2 mms or more at the femoral bone-cement interfaces.

The introduction of this new version of the Oxford knee shows excellent clinical and radiological results which are at least as good as those seen with the Phase 3 Oxford Partial knee replacement. Small adjustments were made to the minimally invasive approach: a reduced invasive incision for ease of implantation. For those surgeons who are concerned over the risks of femoral loosening with the Phase 3 implant, or desire an improved surface area of contact at high angles of flexion, this Twin Peg Oxford Partial knee replacement offers an excellent alternative.

We present a prospective review of the two-year functional outcome of 37 Avon patellofemoral joint replacements carried out in 29 patients with a mean age of 66 years (30 to 82) between October 2002 and March 2007. No patients were lost to follow-up. This is the first independent assessment of this prosthesis using both subjective and objective analysis of outcome. At two years the median Oxford knee score was 39 (interquartile range 32 to 44), the median American Knee Society objective score was 95 (interquartile range 90 to 100), the median American Knee Society functional score was 85 (interquartile range 60 to 100), and the median Melbourne Knee score was 28 (interquartile range 21 to 30). Two patients underwent further surgery. Only one patient reported an unsatisfactory outcome.

We conclude that the promising early results observed by the designing centre are reproducible and provide further support for the role of patellofemoral joint replacement.

Introduction: Existing fatigue studies of ACL fixation have two disadvantages. There is no agreed standard protocol, making comparison of various studies difficult and average results are presented, disregarding data spread. This may be over-optimistic, because approximately half the fixations will not achieve the average level. The effect of data spread can be summarised using the one-sided 80/80 lower tolerance limit (LTL). This LTL indicates the strength that at least 80% of fixations will reach, with an 80% probability. It is commonly used in engineering.

We fatigue-tested a new resorbable composite screw (PLLA/tri-calcium phosphate) and a metal interference screw. We present average data and tolerance limits.

Methods: Porcine BPTB grafts (Ø=9mm) were fixed inside tibial tunnels (Ø=10mm) using composite or metal screws. Each screw was tested for static pull-out strength (n=6) and cyclic loading to failure at 330N and 415N (n=5 each level)

Means and standard deviations of pullout strength were compared. Log-log curves were fitted between force level and cycles to failure. LTLs were calculated.

Results: During static loading, all repairs failed by graft pullout or tissue failure. During cyclic loading, all except one graft fixed with composite screws failed by pullout. Grafts fixed with metal screws failed by bone fracture in 60% of the cases. A composite screw loaded at 300N would last on average 272 cycles or at least (LTL) 7 cycles. At 200N the average and LTL were 38,218 and 966 cycles. Corresponding values for the metal screw were 263 (mean) and 12 (LTL) at 300N; and 12,454 and 564 at 200N.

Discussion and Conclusions: Repairs with metal screw had higher pullout strength, but proved more prone to fatigue. Higher incidence of bone graft fracture in fatigue testing with metal screws suggests that their sharp threads act as stress risers. Fatigue testing of ACL reconstructions shows wide variation, due to several factors. Average levels are therefore over-optimistic and tolerance limits gives a better indication of screw performance. We suggest that tolerance limits should be reported in future studies.

A technique for stabilising the superior tibiofibular joint using an autogenous biceps graft passed through a tibial tunnel is described. The common peroneal nerve should be decompressed and the lateral inferior genicular artery protected. The technique proved to be safe and effective in two patients who were followed for at least two years.

There is a need for the accurate measurement of the outcome after knee surgery. The Oxford Knee Score is being increasingly used since it is reported to be short, simple, inexpensive and validated.

We sent the questionnaire to 346 patients awaiting surgery to the hip or lumbar spine. Only 11% of 141 patients with proximal pathology who denied knee problems gave a maximum score. Their mean score was substantially lower than expected at 28.7 (maximum 48), and was significantly lower than the score of 36.5 obtained from patients after total knee replacement.

We therefore suggest that the frequent coexistence of hip or spinal pathology will significantly alter both the absolute score and any improvement to be expected after knee surgery. Although sensitive to disability originating from the knee the Oxford Knee Score is not sufficiently specific since it is heavily influenced by more proximal pathology.

We describe two patients with obturator dislocation of the hip which was irreducible by described techniques of closed reduction. The first required open reduction using the iliofemoral approach with release of rectus femoris. The second was treated on a traction table which allowed disengagement of the head and, when combined with simultaneous lateral traction, adduction and gradual release of the longitudinal traction, facilitated a smooth reduction. Since the hip is stable in flexion, early mobilisation in an extension-limiting brace avoids the prolonged bed rest traditionally recommended for this injury.