Injury to the dorsomedial cutaneous nerve in the foot may occur after operations for hallux valgus. Pressure neuropathy before operation is also described but remains largely unexplored. We have investigated the incidence of sensory deficit in the great toe before operating for hallux valgus and examined to what extent any deficit was related to the degree of angulation of the joint.

Forty-three patients with a total of 61 great toes with hallux valgus presenting for consideration of surgical correction had their sensation tested in pre-designated zones using a five-filament set of Semmes-Weinstein monofilaments. These allowed good inter-observer reliability with an intra-class correlation coefficient of 0.84.

Sensory symptoms were noted by only 21% of the patients, a measurable reduction in sensation by one monofilament grade or more was found in an additional 44%. No relationship was found between the degree of sensory loss and the degree of angulation.

Patients with symptomatic hallux valgus may have sensory loss in the toe without being aware of it. Normal subjective sensation does not reliably predict normal sensory function. Given the potentially high rates of nerve damage following operations for hallux valgus, we recommend objective sensory testing as part of routine assessment before surgery.

When the Oxford unicompartmental meniscal bearing arthroplasty (UCA) is used in the lateral compartment of the knee 10% of the bearings dislocate. An in-vitro cadaveric study was performed to investigate if the anatomy and joint geometry of the lateral compartment was a contributory factor in bearing dislocation. More specifically, the study investigated if the soft tissue tension of the lateral compartment, as determined by the length of the lateral collateral ligament (LCL), was related to bearing dislocation. A change in length of greater than 2 mm is sufficient to allow the bearing to dislocate.

The Vicon Motion Analysis System (Oxford Metrics, Oxford, UK) was used to assess length changes in the LCL of seven cadaveric knees. Measurements were made of the LCL length through knee flexion and of the change in LCL length when a varus force was applied at a fixed flexion angle. Measurements were made in the normal knee and with the knee implanted with the Oxford prosthesis.

In the intact knee the mean LCL change was 5.5mm (8%) over the flexion range. After implantation with the Oxford UCA the mean change in length was only 1 mm (1%). There was a significant difference in the LCL length at 90° (p=0.03) and 135° (p=0.01) of knee flexion compared to the intact knee. When a varus force was applied the LCL length change of the intact knee (5.4 mm) was significantly different (p=0.02) to that of the knee with the prosthesis implanted (2.7 mm)

This study used a new method to dynamically measure LCL length. It found that after implantation of the Oxford lateral UCA the LCL remains isometric over the flexion range and does not slacken in flexion as it in the normal knee. This would suggest that the soft tissue tension was adequate to contain the bearing within the joint.

However, when a varus force was applied the LCL did not sufficiently resist a displacing force producing an LCL length change greater than 2 mm.

The evidence provided by this study is contradictory. The “lack of change in LCL length through flexion” suggests that the ligament remains tight through range and is unlikely to allow dislocation. However, the amount of distraction possible when an adducting moment is applied is sufficient to allow bearing dislocation. The length tension properties of the lateral structures are therefore implicated in the mechanism of dislocation.

The indications for unicompartmental knee arthroplasty (UKA) can be contentious. Concerns exist about implanting a UKA in younger individuals. It has been reported that it is contra-indicated in patients under the age of 60. The suggestion is that younger patients may compromise their outcome after surgery by their increased activity levels. However, the number of publications with data on UKA in young patients is minimal and the age/activity related criteria for UKA remains unknown.

The aim of the study was 1) to confirm that younger UKA patients have higher activity levels than older patients, and 2) to test the hypothesis that younger, more active patients have inferior outcome when compared to older less active patients.

Fifty consecutive patients undergoing UKA who were under 60 years (Group Y) and 50 patients over 60 years (Group O) were recruited. Indications were anteromedial arthritis with full thickness lateral compartment cartilage, a functioning ACL and a correctible varus. All patients underwent Oxford UKA using the minimally invasive technique. This device employs an unconstrained fully congruous meniscal bearing. Outcome was evaluated using Knee Society Scores. Activity level was documented using Tegner Activity Score.

Average age of patients for group Y and O was 55 and 68 years respectively. Minimum follw-up was 2 years. pre-op. knee scores were comparable for each group. (y: 38.8, O: 35.8) and patients in both groups siginificantly improved after surgery. A significant difference in Tegner score was found between the two groups after surgery (y:4.1, O:2.6). More than 50% of younger patients regularly participated in high demand activities like skiing, tennis and manual labour. No statistically significant differences in any other post op. knee scores or complication rate were found despite adequate study power.

Younger patients have increased activity levels after UKA when compared to an older age group. There is no evidence that the outcome of UKA in younger more active patients will be inferior to those who are older and more sedentary.

There are numerous ankle and hindfoot scores in existence, which have been devised and used to assess surgical interventions. All have in common that there has been little or no work done to demonstrate their validity, reliability or sensitivity to change. Which score one chooses to use for the assessment of outcome will at present depend largely on personal preference.

We have undertaken a study to assess four of the most commonly used scores, those of Mazur (1978), Takakura (1990), AOFAS (1994) and Kofoed (1995) as well as a little used but well designed score, The Foot Function Index (1991).

A cohort of twenty patients who had undergone a unilateral total ankle replacement (STAR) for rheumatoid or osteoarthritis were assessed by a single observer. The time following operation ranged from six to 48 months. All completed the above scores as well as a SF36 questionnaire. Using the SF36 as a “Gold standard” the scores were compared, both in terms of their overall results and also more specifically in terms of subsections such as pain and function.

Our results, though not to be interpreted as validation, do give some rational basis for the choice of score to use in assessing total ankle replacements.

Injury to the dorsomedial cutaneous nerve has been identified as a potentially frequent occurrence after hallux valgus surgery. The existence of pre-operative pressure neuropathy is also described but remains largely unexplored. This study was performed to investigate the incidence of pre-operative sensory deficit in the hallux valgus toe, and to examine to what extent any deficit was related to the degree of joint angulation.

A cohort of 43 patients (61 hallux toes) presenting for consideration of surgical correction had their sensation tested in pre-designated sensory zones using a five-filament set of Semmes-Weinstein monofilaments. These allowed good inter-observer reliability with an ICC (intra-class correlation coefficient) of 0.84 overall.

Whilst sensory symptoms were self reported in only 21% of the feet, a measurable reduction in sensation by one monofilament grade or more was found in an additional 44% of the feet. No relationship was found between the degree of sensory loss and degree of angulation.

Patients with symptomatic hallux valgus may have sensory loss of the toe despite not being aware of the deficit. Normal subjective sensation does not reliably predict normal sensory function. Given the potentially high rates of intra-operative nerve damage in hallux surgery we recommend objective sensory testing as part of routine pre-operative assessment.

The purpose of this study was to determine the rate of polyethylene wear in a fixed bearing knee replacement in order to establish a norm against which mobile bearing implants can be judged.

Method: Eighteen all polyethylene tibial components were retrieved when a St Georg Sled unicompartmental replacement was being revised. This prosthesis has a biconvex femoral component and a totally flat tibia; thus point loading occurs on at implantation. The implants had been in situ between 6 and 110 months, revision was predominantly for progression of the arthritic process.

Linear wear was measured using an electronic micrometer and volumetric wear by creating a mould of the defect using dental wax, and subsequently weighing the wax.

Results: All components developed dishing which varied in orientation but matched the alignment of the femoral component. A near congruous articulation was thus produced correctly aligned for that particular arthroplasty. The mean linear penetrative wear for the group was 0.33mm (0.09mm per year) and the volumetric wear 124mm³ (26mm³ per year). The rate of wear seemed greatest during the second year.

Conclusion: The wear rate for this totally non congruous implant was much less than anticipated. The linear penetrative wear is comparable to that reported for Charnley hip replacement though more than for a fully congruent mobile UKR. The volumetric wear is much lower than that thought to cause osteolysis. The surprisingly low wear rate suggests that the need for mobile bearing UKRs, with their greater technical demands, should be questioned.

Before proceeding to longer-term studies, we have studied the early clinical results of a new mobile-bearing total knee prosthesis in comparison with an established fixed-bearing device. Patients requiring bilateral knee replacement consented to have their operations under one anaesthetic using one of each prosthesis. They also agreed to accept the random choice of knee (right or left) and to remain ignorant as to which side had which implant. Outcomes were measured using the American Knee Society Score (AKSS), the Oxford Knee Score (OKS), and determination of the range of movement and pain scores before and at one year after operation.

Preoperatively, there was no systematic difference between the right and left knees. One patient died in the perioperative period and one mobile-bearing prosthesis required early revision for dislocation of the meniscal component.

At one year the mean AKSS, OKS and pain scores for the new device were slightly better (p < 0.025) than those for the fixed-bearing device. There was no difference in the range of movement.

We believe that this is the first controlled, blinded trial to compare early function of a new knee prosthesis with that of a standard implant. It demonstrates a small but significant clinical advantage for the mobile-bearing design.

Introduction: The indications for unicompartmental knee arthroplasty (UKA) can be contentious. Concerns exist about implanting a UKA in younger individuals and it has been reported that the procedure is contra-indicated in patients under the age of 60. The suggestion is that younger patients may compromise their outcome after surgery by their increased activity levels. However, the number of publications with data on UKA in young patients is minimal and the age/activity related criteria for UKA remains unknown.

Aim: The aim is twofold: 1) to confirm that younger UKA patients have higher activity levels than older patients, and 2) to test the hypothesis that younger, more active patients have inferior outcome when compared to older less active patients.

Materials and methods: Fifty consecutive patients undergoing UKA who were under 60 years old at the time of surgery (Group Y) and 50 patients over 60 years (Group O) were recruited. Indications were anteromedial arthritis with full thickness lateral compartment cartilage, a functioning ACL and a correctible varus deformity. All patients underwent Oxford UKA using the minimally invasive technique. This device employs an unconstrained fully congruous meniscal bearing. Outcome was evaluated using the American Knee Society Score (AKSS). Activity level was documented using the established Tegner Activity Score.

Results: The average age of patients for group Y and O was 55 years and 68 years respectively. Minimum follow up for both groups was 2 years. Pre-operative AKSS scores were comparable for each group (Group Y = 38.8, Group O = 35.8) and patients in both groups significantly improved after surgery. A significant difference in Tegner score was found between groups after surgery (Group Y = 3.9, Group O = 2.6). It was found that 40% of younger patients regularly participate in high demand activities like skiing, tennis, hard manual labour and swimming. No statistically significant difference in any other post operative knee scores or complication rate were found despite adequate study power.

Conclusions: Younger patients have increased activity levels after UKA when compared to an older age group. There is no evidence that the outcome of UKA in younger more active patients will be inferior to those who are older and more sedentary.

Purpose: As part of the step-wise introduction of a meniscal-bearing total knee replacement (Oxford TMK) we needed to know, before proceeding to longer term studies, whether its early clinical results were at least as good as those of an established fixed bearing device (AGC).

Material and Methods: With ethical approval, patients requiring bilateral knee replacement for osteoarthritis consented to have the operations under one anaesthetic using one of each prosthesis; to accept random choice of knee; and to remain ignorant which side was which. American Knee Society Scores, Oxford Knee Scores, ROM and pain scores were to be recorded preoperatively and at one year. By January 2001, 40 patients had reached one year and data is available for 36.

Results: Preoperatively there was no difference between the two knees. One patient died in the peri-operative period.

Results at one year (TMK first): AKSS(Knee) 91.6 / 84.1 (p=0.003), OKS 39.8 / 37.6 (p=0.006), ROM 104 / 104 (p=0.364), Pain (AKSS) 47.3 / 41.7 (p=0.01), Pain (OKS) 3.5 / 2.9 (p=0.006).

Conclusion: The TMK performed as well as the AGC. Its AKSS, OKS and pain scores were significantly better. We believe this controlled, blinded trial is the first to have compared the function of a new knee prosthesis with a standard implant before marketing; and the first to have demonstrated a significant clinical advantage for a meniscal-bearing over a fixed bearing TKR. The comparison of bilateral implants in the same patient can reveal significant differences while putting at risk many fewer subjects than would be needed for a classical twocohort RCT.

We performed a prospective, double-blind, randomised, clinical trial to investigate the efficacy of two regimes of rehabilitation for knees with anterior cruciate ligament deficiency (ACLD). Fifty ACLD patients were randomly allocated to one of two treatment groups: a programme of muscle strengthening (T) or a programme designed to enhance proprioception and improve hamstring contraction reflexes (P). An indirect measure of proprioception, the reflex hamstring contraction latency (RHCL), and a functional scoring system were used to record the status of the knee before and after the 12-week course of physiotherapy. Sagittal knee laxity was also measured. There was improvement in mean RHCL and in the mean functional score in both groups after treatment. The improvement in group P was significantly greater than that in group T. There was no significant change in joint laxity after treatment in either group. In both groups there was a positive correlation between improvement in RHCL and functional gain.

Failure of conservative treatment is the usual indication for the reconstruction of a knee with deficiency of the anterior cruciate ligament (ACL) and this depends on subjective judgement. The ability of muscles to protect the subluxing joint by reflex contraction could provide an objective measurement. We have studied 30 patients with unilateral ACL deficiency by measuring the latency of reflex hamstring contraction. We found that the mean latency in the injured leg was nearly twice that in the unaffected limb (99 ms and 53 ms respectively). There was a significant correlation between the differential latency and the frequency of 'giving way' indicating that functional instability may be due, in part, to loss of proprioception. Measures of proprioception, including reflex hamstring latency, may be useful in providing an objective assessment of the efficacy of conservative treatment and the need for surgery.