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.

The latest government targets state that by the end of 2005 the maximum waiting time for an outpatient appointment will be 3 months. These recommendations will not only increase the size of the outpatient clinics, but also the resources required thereafter. The purpose of this study was to analyse the outcome of new knee referrals to one consultant’s knee outpatient service in order to quantify the resources required to investigate and treat these patients.

All new patients attending one consultant’s knee out-patient service in the time period January 1st 1997 to December 31st 1997 were prospectively entered into a database recording patient details, source of referral and provisional diagnosis.

Eighteen months after the time period a cohort of 200 patients was randomly selected and the notes were analysed retrospectively. The number of outpatient appointment episodes (OPAs), MRI scans, physiotherapy referrals and surgical episodes generated were recorded for each patient.

Analysis of the initial database records show that a total of 662 new knee referrals were seen in 1997. 52% (341) were made up of the five most common diagnoses, these being osteoarthritis, anterior knee pain, major anterior cruciate ligament injury, medial ligament injury and medial meniscus injury.

Retrospective analysis of the 200 patient notes revealed that these patients required a total of 511 OPAs, 38 MRI scans, 178 courses of physiotherapy and 93 surgical episodes (53 elective and 40 daycase/emergency). These figures can be extrapolated to account for the total number of patients seen:

The resource implications of a new knee referral are substantial. Extra resources must accompany each new patient, otherwise, although government targets will be reached the time taken to complete each patient’s treatment will become longer. It is imperative that before an agreement is made to see new patients the resources required to manage them are in place.

Nine patients underwent arthrodesis of the knee using a customised coupled nail (the Mayday arthrodesis nail), five after infected arthroplasty, one following failed arthrodesis, one for intractable anterior knee pain, one for Charcot instability and one after trauma. Comparison was made with 17 arthrodeses, eight undertaken using external fixation, four with dual compression plates, and five with long Küntscher nails. Union was achieved in all patients (100%) at a mean time of ten months using the customised implant. There were no complications despite early weight-bearing. No further procedures were required. This contrasted with a rate of union of 53% and a complication rate of 76% with alternative techniques. Of this second group, 76% required a further operative procedure.

We compared the Mayday arthrodesis nail with other techniques of arthrodesis of the knee. The differences in the need for further surgery and occurrence of complications were statistically significant (p < 0.001), and differences in the rate of nonunion and inpatient stay of less than three weeks were also significant (p < 0.05) using Fisher’s exact test.

We conclude that a customised coupled intramedullary nail can give excellent stability allowing early weight-bearing, and results in a high rate of union with minimal postoperative complications.

The aim of this study was to investigate the hypothesis that unicompartmental knee replacement (UKR) of a single arthritic tibio femoral compartment can slow the progression of arthritis to the other compartment.

Method: Since 1974, a prospective database has been established in Bristol to register and follow up the results of unicompartmental knee replacement. Forty two prostheses that had survived for more than 10 years were examined using the Ahlbach radiological scoring system and compared to a control group of patients from the Bristol “OA 500” series, in which patients being treated conservatively for gonarthritis were regularly reviewed by clinical scoring and radiological analysis. The groups were sex matched.

All AP and lateral standing knee radiographs at entry and 8 years were scored using the Ahlbach scoring system. The Ahlbach system has been shown to have good inter and intra observer correlation, and to relate closely to pathological findings at operation. An intra and inter observer error study of our results confirmed good correlation.

Results: The groups were well matched but the OA 500 group showed a lower average age, though not a significant difference (62 years compared to 67 years). The lateral compartment of all knees in both groups were Ahlbach grade 0 or 1 group before operation or entry to the OA 500 register.

In the UKR group, four out of 42 knees showed progression of a single Ahlbach grade (9.5%). 2 revisions for arthritic progression were added to this group making a total of six out of 42 (14.3%). In the control group 12 of the 42 knees progressed by one or two Ahlbach grades and a further case underwent surgery making a total of 13 (31%). This difference was significant (p< 0.01).

Conclusion: Recent studies have shown that with a better understanding of design, improved selection of patients and better surgical technique, a UKR can have at least as good, if not better, results than a TKR at 5 year follow up, and has benefits of preservation of anatomy, earlier rehabilitation, preservation of bone stock and easier revision. Our radiological findings in this study will need to be correlated with further randomised prospective clinical studies, but suggest that progression of Osteoarthritis is reduced by UKR, and that this should be an additional stated benefit of this surgical technique.

Introduction: Traditionally adolescent anterior knee pain is considered to be a self limiting condition with no long term sequelae. However recently two publications have suggested the condition may be longer lasting. We wish to suggest that adolescent anterior knee pain may lead to patello femoral arthritis.

Method: We have carried out a comparative study assessing the incidence of previous adolescent anterior knee in patients who underwent patello femoral replacement for isolated patello femoral arthritis and have compared them with a matched group of patients who had medial unicompartmental replacement for isolated medial compartment arthritis without patello femoral disease.

All patients were sent a postal questionnaire enquiring about adolescent anterior knee pain, knee injury and patella instability.

Results: Ninety-three PFR patients and 86 UKR patients replied. The incidence of adolescent AKF and patella instability was higher in the PFR.group.

Conclusion: Adolescent anterior knee pain may not always be a benign self limiting condition since this as well as patella injury and instability was associated with subsequent isolated patello femoral arthritis.

The aim of this study was to demonstrate the effectiveness of a customised coupled arthrodesis nail.

Knee arthrodesis is now infrequently performed and is usually reserved as a salvage for infected Joint arthroplasty or occasionally for intractable pain. Many methods have been used. Recently locked intramedullary coupled nails have gained in popularity. To deal with all size combinations a large inventory is required. We wish to report our series using a customised implant and to compare the outcome with other methods of knee arthrodesis.

Nine patients underwent arthrodesis using this implant, six following infected arthroplasty, two for intractable anterior knee pain and following trauma. Comparison was made with 17 arthrodeses performed since 1993 using external fixation (8), plates (4), and long K-nails (5). Union was achieved in nine patients (100%) at a mean time of 10 months using the customised implant. There were no complications despite early weight-bearing. No further procedures were required. This contrasted with a union rate of 65% with a 76% complication rate using alternative techniques. Seventy six percent of this second group required a further operative procedure.

We conclude that a customised coupled intramedullary nail can give excellent stability allowing early weight-bearing, and results in a high union rate with minimal post-operative complications. The differences in need for further surgery and occurrence of complications were statistically significant (p< 0.001), and differences in in-patient stay and non-union rate were also significant (p< 0.05) using Fisher’s exact test.

The aim of this study was to analyse the kneeling ability of patients before and at one and two years after total (TKR), unicompartmental (UKR) and selective patellofemoral (PFR) knee arthroplasty, for osteoarthritis. Method: Data was prospectively collected on 253 knees, which underwent either TKR, UKR or PFR. A kneeling score was obtained by analysis of the relevant section of the Oxford Knee Score questionnaire. Scores were obtained pre-operatively and at 1 and 2 years post-operatively (minimum score 0, maximum 4). Absolute values and change following arthroplasty were recorded. Correlations with pain and other knee functions were also made.

Results: Kneeling ability prior to surgery was poor in all three groups (mean score 0.7 out of 4) and improved significantly after surgery (mean score at one year 1.13 and at two years 1.46 out of 4) (P< 0.001). Kneeling ability at 1 year differed significantly with operation type (p = 0.02). Kneeling ability improved most in the first year post-operatively but continued to improve between one and two years although the final function was still not good. Kneeling ability was best in UKR and worst in PFR, with the difference between these prostheses being statistically significant (P< 0.001).

Conclusion: Kneeling ability in osteoarthritic knees is poor but improves with arthroplasty. However, the majority of patients will still have difficulty kneeling.

Aim: To assess the functional results of revision TKR with the PFC/TC3 system, and to correlate this with the reasons for revision and restoration of joint height.

Method: One hundred and fifty three patients underwent revision TKR using the PFC/TC3 system. Data was prospectively collected (using the Bristol Knee Score) pre-operatively and at a mean of 4.2 years post-revision. Forty three revisions were for infection and 81 revisions were for aseptic loosening. Measurements of the joint height were made pre and post-operatively using Figgie’s method and were divided into three groups: lower by more than 5mm, restored and elevated more than 5mm. Use of distal augments and polyethylene thickness were recorded.

Results: The mean pre-op function score was 12 and post-operatively was 19 for the infection group and 20 for the aseptic loosening group. Revision after initial UKR gave a mean score of 21, while revision after TKR gave a mean score of 18 (max 27). Knees in which the joint line was elevated by more than 5 mm had a mean score of 17 while those where the joint line was restored had a mean score of 1 9. Recent increasing use of distal augments improved the joint line and results.

Conclusion: Revision using the PFC/TC3 system produced acceptable medium term functional results and good survival. Better restoration of joint line and functional results were achieved by distal femoral rather than proximal tibial augmentation.

Objective: To report the survivorship rate and clinical outcome of a large series of lateral unicompartmental replacements.

Method: 88 lateral St Georg Sled LTKRS were performed between 1978 and 1999. Clinical and radiological data was prospectively recorded at regular follow up and only 5 knees were lost during the 22 year period.

Results: 15 knees were revised after an average of 8 years. (eight for progressive arthritis, six for loosening and four for femoral fracture) 29 patients (30 knees) died during the course of the study. At final follow up (average 9 years) 50 of the 63 remaining knees were rated as good or excellent, nine as fair and nine poor. The mean range of flexion was 110°.

At 10 years the cumulative survival rate was 83% and at 15 years 78% (10 knees at risk). The “worst case scenario” where knees with pain or lost to follow up are added to revisions shows a 10 year survivorship of 74%.

Conclusion: Although the results are not as good as medial UKR. These clinical outcomes suggest that the conservative surgical procedure of lateral UKR with the fixed bearing St George Sled prosthesis can give acceptable results in the uncommon situation of severely symptomatic isolated lateral tibio femoral arthritis.

Purpose: To compare the ten-year survivorship results of an established total and medial compartment knee replacement performed in a single centre over an eighteen year period.

Method: Since 1978 knee replacements have been prospectively recorded in Bristol on a database. Regular clinical and radiological review has been undertaken every two or three years up to twenty years. 408 medial St Georg Unicompartmental replacements and 531 Kinematic total knee replacements have been subject to survivorship analysis using three failure end points. One - revision or removal of the implant. Two – revision or removal and moderate or severe pain. Three – the worst case including all patients lost to follow-up.

Results: The follow-up rate was 97% in both groups. 212 patients (562 knees) died and 31 patients (35 knees) were lost to follow-up. At ten years 25 medial Sled and 20 Kinematic knee arthroplasties had been revised. There was no significant difference (p > 0.05) in the number of good and excellent results. The mean range of movement at the last follow-up was 109 degrees for the medial Sled and 100 degrees for the Kinematic (p< 0.01). 94% of the medial Sled patients obtained a range of movement equal to or greater than 90 degrees whereas only 84% of Kinematic patients obtained this range (p < 0.05).

The ten-year survivorship figures were similar for both groups. Revision as the end point was 87.5% for the medial Sled and 89.6% for the Kinematic knees. When moderate and severe pain was considered in addition to revision ten-year survivorship was 79.4% in both groups. The worst case survivorship was also 74% in both groups.

Conclusion: The ten-year survivorship results of a fixed bearing, non-congruous, Unicompartmental arthroplasty are as good as those of a total knee replacement when performed in a single centre by two consultant surgeons and a variety of trainees. The advantages of a more rapid recovery and better quality result are offset by an easier though slightly higher revision rate.

We describe 88 knees (79 patients) with lateral unicompartmental osteoarthritis which had been treated by the St Georg Sled prosthesis.

At a mean follow-up of nine years (2 to 21) 15 knees had revision surgery, nine for progression of arthritis, six for loosening, four for breakage of a component and four for more than one reason. Six patients complained of moderate or severe pain at the final follow-up. Only five knees were lost to follow-up in the 21-year period.

We performed survivorship analysis on the group using revision for any cause as the endpoint. At ten years the cumulative survival rate was 83%, and at 15 years, when ten knees were still at risk, it was 74%.

Based on our clinical results and survival rate the St Georg Sled may be considered to be a suitable unicompartmental replacement for isolated lateral compartment osteoarthritis.

Traditional dogma states that anterior knee pain in adolescence does not lead to patello-femoral arthritis. However analysis of 642 new knee referrals seen in one year showed that over 25% had anterior knee pain and that patients were of all ages. This lead to us questioning whether anterior knee pain or adolescent chondromalacia patellae is in fact a benign self limiting condition.

Method: A postal questionnaire was sent to 150 patients who had undergone isolated patello femoral replacement (PFR) enquiring about patella problems earlier in life. The same questionnaire was sent to a matched group of patients who had undergone unicompartmental replacement; because of the selection policy of the unit, these would not have had changes of patellofemoral arthritis.

Results: 118 patients who had undergone PFR retumed the form. 107 were female; the average age at surgery was 66 years. 26 (22%) reported adolescent anterior knee pain at an average age of 18. 112 forms were returned form the UKR group in which females predominated and who had an average age at surgery of 67 years. Only 7 (6%) reported adolescent anterior knee pain, at an average age of 19. 16 (14%) of the PFR group reported adolescent patella instability as opposed to 1 on the UKR group.

Discussion: The finding that significantly more patients with isolated patello-femoral arthritis had suffered from adolescent anterior knee pain suggests a possible causal relationship. Further long-term studies are needed to determine whether adolescent anterior knee pain is benign, as traditionally believed, or whether certain subsets are precursors of patello-femoral arthritis.

Purpose: This study analyses the kneeling ability of patients following Unicompartmental knee replacement (UKR), Patellofemoral replacement (PFR) and Total knee replacement (TKR).

Method: Data was prospectively collected on 272 knees (254 patients) that had undergone various forms of arthroplasty procedures for osteoarthritis of the knee. All patients completed the Oxford Knee Questionnaire preoperatively and 1 year postoperatively, thus graded their kneeling ability into one of 5 categories. Absolute values and change following arthroplasty were recorded. In addition the reported kneeling ability of 75 patients was checked by clinical examination.

Results: Preoperatively only 2% of all patients could kneel with PFR group being more able than the others (UKR 0%, TKR 0% and PFR 6%). In all groups the kneeling ability was better one year following replacement than preoperatively (23% of UKR, 18% of TKR and 9% of PFR) being able to kneel with little or no difficulty.

Conclusions: No form of arthroplasty used resulted in good kneeling ability, though this function was always improved particularly by UKR. Good range of movement and younger age appeared to correlate with better kneeling ability but many patients thought they had been told not to kneel and reported less ability than they demonstrated on examination. Instruction to avoid kneeling seems unnecessary.

We have studied the long-term outcome of 408 primary medial St George Sled unicompartmental arthroplasties of the knee and 531 primary Kinematic total knee arthroplasties using survivorship analysis. The operations were performed by a number of surgeons under the supervision of two consultants at one orthopaedic centre. Prospective clinical assessment was carried out before and at 2, 5, 8, 10, 12 and 15 years after operation. Failure was defined as follows: revision or removal of the implant; the presence of moderate or severe pain; or ‘worst-case’ with all patients lost to follow-up.

Cumulative survival rates at ten years were calculated using life tables. The follow-up rate was 97%. At ten years, 25 medial sled arthroplasties and 20 Kinematic knee arthroplasties had been revised. With revision or removal as the survivorship endpoint at ten years there was a success rate of 87.5% for the medial sled and 89.6% for the Kinematic knee arthroplasty. When moderate or severe pain was included these rates became 79.4% for both arthroplasties. There was no statistically significant (p > 0.05) difference between the rates of survival for the two arthroplasties using either of the endpoint criteria.

Good or excellent results were recorded for 77.9% of the medial sled knees and 75.1% for the Kinematic knees. The former had 93.8% of cases with a final range of movement in excess of 90° compared with 83.7% for the Kinematic knees (p < 0.01). We conclude that at a single orthopaedic centre in the UK, the St Georg Sled medial compartment arthroplasty for appropriate specific indications offers predictable survivorship at ten years which is comparable with that of the Kinematic total knee arthroplasty.

We present a prospective review of the outcome of 76 Lubinus patellofemoral arthroplasties carried out in 59 patients between 1989 and 1995. At a mean follow-up of 7.5 years, 62 knees in the 48 patients were reviewed; 11 patients (14 knees) had died. None was lost to follow-up.

The clinical outcome using the Bristol Knee Scoring system was satisfactory in 45% of the cases. Maltracking of the patella, resulting in lateral tilt, subluxation and polyethylene wear, was the most common complication (32%). Revision surgery was carried out in 21 knees (28%) giving a cumulative survival rate of 65% (confidence interval (CI) 49 to 77) at eight years. The survival rate for revision and moderate pain was 48% (CI 36 to 59) at six years. Progression of arthritis was seen in seven cases (9%). In five of these (6.5%), the symptoms were severe enough to need revision surgery. Due to the high proportion of unsatisfactory results, we have discontinued the use of this prosthesis.

Failure of a unicompartmental knee replacement (UKR) may be caused by progressive osteoarthritis of the knee and/or failure of the prosthesis. Limb alignment can influence both of these factors. We have examined the fate of the other compartments and measured changes in leg alignment after UKR.

A total of 50 UKRs was carried out on 45 carefully selected patients between 1989 and 1992. At operation, deliberate attempts were made to avoid overcorrection of the deformity. Four patients died, one patient was lost to follow-up and two knees were revised before review which was at a minimum of five years. Standard long-leg weight-bearing anteroposterior views of the knee and skyline views of the patellofemoral joint were taken before and at eight months and five years after operation. The radiographs of the remaining 43 knees were reviewed twice by blind and randomised assessment to measure the progression of osteoarthritis within the joints. Overcorrection of the deformity in the coronal plane was avoided in all but two knees. Only one showed evidence of progression of osteoarthritis within the patellofemoral joint, and this was only identified in one of the four assessments. Deterioration in the state of the opposite tibiofemoral compartment was not seen. Varus deformity tended to recur. Recurrent varus of 2° was observed between eight months and five years after operation. There was no correlation between the postoperative tibiofemoral angle and the extent of recurrent varus recorded at five years. Changes in alignment may be indicative of minor polyethylene wear or of subsidence of the tibial component.

The incidence of progressive osteoarthritis within the knee was very low after UKR. Patients should be carefully selected and overcorrection of the deformity be avoided.

Patella infera may occur after reconstruction of the anterior cruciate ligament (ACL), high tibial osteotomy and total knee replacement (TKR). Restriction of movement of the knee and pain may result. Our aim was to compare the incidence and to assess the effects of patella infera after TKR and unicompartmental knee replacement (UKR).

We reviewed radiographs of the knees of 84 patients who had had either TKR or UKR as part of a randomised, controlled trial. The length of the patellar tendon was measured on serial radiographs taken before, at eight months and at five years after operation.

There was no significant change in the length of the patellar tendon after UKR, but a significant reduction was observed after TKR. Five years after the operation, the shortening of the tendon had increased to a mean of 3.5 mm. Of the knees with TKR reviewed at five years, 34% developed patella infera, defined as 10% or more of shortening, compared with 5% of those with UKR. Shortening was greatest in those knees which had required a lateral release; in this subgroup the mean shortening was 7.2 mm. Shortening correlated with restriction of movement and pain in the knee.

Our study has shown that patella infera develops in most patients after TKR with lateral release, and in approximately 25% of patients after TKR without this additional procedure. Patella infera rarely occurs after UKR. It is associated with restriction of movement and pain in the knee. It may be an effect of the more extensive exposure required to perform TKR and may, in part, explain the better clinical results of UKR.

We randomised 102 knees suitable for a unicompartmental replacement to receive either a unicompartmental (UKR) or total knee replacement (TKR) after arthrotomy. Both groups were well matched with a predominance of females and a mean age of 69 years.

Patients in the UKR group showed less perioperative morbidity, but regained knee movement more rapidly and were discharged from hospital sooner.

At five years, two UKRs and one TKR had been revised; another TKR was radiologically loose. All other knees appeared to be clinically and radiologically sound.

Pain relief was good in both groups but the number of knees able to flex ≥ 120° was significantly higher in the UKR group (p < 0.001) and there were more excellent results in this group.

Our findings have shown that UKR gives better results than TKR and that this superiority is maintained for at least five years.