The aim of this study was to estimate the incremental use of resources, costs, and quality of life outcomes associated with surgical reconstruction compared to rehabilitation for long-standing anterior cruciate ligament (ACL) injury in the NHS, and to estimate its cost-effectiveness. A total of 316 patients were recruited and randomly assigned to either surgical reconstruction or rehabilitation (physiotherapy but with subsequent reconstruction permitted if instability persisted after treatment). Healthcare resource use and health-related quality of life data (EuroQol five-dimension five-level health questionnaire) were collected in the trial at six, 12, and 18 months using self-reported questionnaires and medical records. Using intention-to-treat analysis, differences in costs, and quality-adjusted life years (QALYs) between treatment arms were estimated adjusting for baseline differences and following multiple imputation of missing data. The incremental cost-effectiveness ratio (ICER) was estimated as the difference in costs divided by the difference in QALYs between reconstruction and rehabilitation.Aims
Methods
Routinely collected patient-reported outcome measures (PROMs) have been useful to quantify and quality-assess provision of total hip arthroplasty (THA) and total knee arthroplasty (TKA) in the UK for the past decade. This study aimed to explore whether the outcome following primary THA and TKA had improved over the past seven years. Secondary data analysis of 277,430 primary THAs and 308,007 primary TKAs from the NHS PROMs programme was undertaken. Outcome measures were: postoperative Oxford Hip/Knee Score (OHS/OKS); proportion of patients achieving a clinically important improvement in joint function (responders); quality of life; patient satisfaction; perceived success; and complication rates. Outcome measures were compared based on year of surgery using multiple linear and logistic regression models.Aims
Methods
To estimate the measurement properties for the Oxford Knee Score (OKS) in patients undergoing revision knee arthroplasty (responsiveness, minimal detectable change (MDC-90), minimal important change (MIC), minimal important difference (MID), internal consistency, construct validity, and interpretability). Secondary data analysis was performed for 10,727 patients undergoing revision knee arthroplasty between 2013 to 2019 using a UK national patient-reported outcome measure (PROM) dataset. Outcome data were collected before revision and at six months postoperatively, using the OKS and EuroQol five-dimension score (EQ-5D). Measurement properties were assessed according to COnsensus-based Standards for the selection of health status Measurement Instruments (COSMIN) guidelines.Aims
Methods
To calculate how the likelihood of obtaining measurable benefit from hip or knee arthroplasty varies with preoperative patient-reported scores. Existing UK data from 222,933 knee and 209,760 hip arthroplasty patients were used to model an individual’s probability of gaining meaningful improvement after surgery based on their preoperative Oxford Knee or Hip Score (OKS/OHS). A clinically meaningful improvement after arthroplasty was defined as ≥ 8 point improvement in OHS, and ≥ 7 in OKS.Aims
Methods
The aim of this study was to determine the long-term risk of undergoing knee arthroplasty in a cohort of patients with meniscal tears who had undergone arthroscopic partial meniscectomy (APM). A retrospective national cohort of patients with a history of isolated APM was identified over a 20-year period. Patients with prior surgery to the same knee were excluded. The primary outcome was knee arthroplasty. Hazard ratios (HRs) were adjusted by patient age, sex, year of APM, Charlson comorbidity index, regional deprivation, rurality, and ethnicity. Risk of arthroplasty in the index knee was compared with the patient’s contralateral knee (with Aims
Patients and Methods
The aim of the British Association for Surgery of the Knee (BASK) Meniscal Consensus Project was to develop an evidence-based treatment guideline for patients with meniscal lesions of the knee. A formal consensus process was undertaken applying nominal group, Delphi, and appropriateness methods. Consensus was first reached on the terminology relating to the definition, investigation, and classification of meniscal lesions. A series of simulated clinical scenarios was then created and the appropriateness of arthroscopic meniscal surgery or nonoperative treatment in each scenario was rated by the group. The process was informed throughout by the latest published, and previously unpublished, clinical and epidemiological evidence. Scenarios were then grouped together based upon the similarity of clinical features and ratings to form the guideline for treatment. Feedback on the draft guideline was sought from the entire membership of BASK before final revisions and approval by the consensus group.Aims
Materials and Methods
The aims of this study were to compare the use of resources, costs, and quality of life outcomes associated with subacromial decompression, arthroscopy only (placebo surgery), and no treatment for subacromial pain in the United Kingdom National Health Service (NHS), and to estimate their cost-effectiveness. The use of resources, costs, and quality-adjusted life-years (QALYs) were assessed in the trial at six months and one year. Results were extrapolated to two years after randomization. Differences between treatment arms, based on the intention-to-treat principle, were adjusted for covariates and missing data were handled using multiple imputation. Incremental cost-effectiveness ratios were calculated, with uncertainty around the values estimated using bootstrapping.Aims
Patients and Methods
The appropriate management for patients with a degenerative tear
of the rotator cuff remains controversial, but operative treatment,
particularly arthroscopic surgery, is increasingly being used. Our
aim in this paper was to compare the effectiveness of arthroscopic
with open repair of the rotator cuff. A total of 273 patients were recruited to a randomised comparison
trial (136 to arthroscopic surgery and 137 to open surgery) from
19 teaching and general hospitals in the United Kingdom. The surgeons
used their usual preferred method of repair. The Oxford Shoulder
Score (OSS), two years post-operatively, was the primary outcome
measure. Imaging of the shoulder was performed at one year after
surgery. The trial is registered with Current Controlled Trials,
ISRCTN97804283.Aims
Patients and Methods
The aim of this to study was to compare the previously unreported
long-term survival outcome of the Oxford medial unicompartmental
knee arthroplasty (UKA) performed by trainee surgeons and consultants. We therefore identified a previously unreported cohort of 1084
knees in 947 patients who had a UKA inserted for anteromedial knee
arthritis by consultants and surgeons in training, at a tertiary
arthroplasty centre and performed survival analysis on the group
with revision as the endpoint.Aims
Patients and Methods
We assessed the orientation of the acetabular
component in 1070 primary total hip arthroplasties with hard-on-soft, small
diameter bearings, aiming to determine the size and site of the
target zone that optimises outcome. Outcome measures included complications,
dislocations, revisions and ΔOHS (the difference between the Oxford
Hip Scores pre-operatively and five years post-operatively). A wide
scatter of orientation was observed (2 This study demonstrated that with traditional technology surgeons
can only reliably achieve a target zone of ±15°. As the optimal
zone to diminish the risk of dislocation is also ±15°, surgeons
should be able to achieve this. This is the first study to demonstrate
that optimal orientation of the acetabular component improves the
functional outcome. However, the target zone is small (± 5°) and
cannot, with current technology, be consistently achieved. Cite this article:
The primary aim of this study was to develop
a patient-reported Activity &
Participation Questionnaire (the
OKS-APQ) to supplement the Oxford knee score, in order to assess
higher levels of activity and participation. The generation of items
for the questionnaire involved interviews with 26 patients. Psychometric
analysis (exploratory and confirmatory factor analysis and Rasch
analysis) guided the reduction of items and the generation of a
scale within a prospective study of 122 relatively young patients
(mean age 61.5 years (42 to 71)) prior to knee replacement. A total
of 99, completed pre-operative and six month post-operative assessments
(new items, OKS, Short-Form 36 and American Knee Society Score). The eight-item OKS-APQ scale is unidimensional, reliable (Cronbach’s
alpha 0.85; intraclass correlation coefficient (ICC) 0.79; or 0.92
when one outlier was excluded), valid (r >
0.5 with related scales)
and responsive (effect size 4.16). We recommend that it is used with the OKS with adults of all
ages when further detail regarding the levels of activity and participation
of a patient is required. Cite this article:
We conducted a randomised controlled trial to
determine whether active intense pulsed light (IPL) is an effective treatment
for patients with chronic mid-body Achilles tendinopathy. A total
of 47 patients were randomly assigned to three weekly therapeutic
or placebo IPL treatments. The primary outcome measure was the Victorian
Institute of Sport Assessment – Achilles (VISA-A) score. Secondary
outcomes were a visual analogue scale for pain (VAS) and the Lower
Extremity Functional Scale (LEFS). Outcomes were recorded at baseline,
six weeks and 12 weeks following treatment. Ultrasound assessment
of the thickness of the tendon and neovascularisation were also
recorded before and after treatment. There was no significant difference between the groups for any
of the outcome scores or ultrasound measurements by 12 weeks, showing
no measurable benefit from treatment with IPL in patients with Achilles tendinopathy. Cite this article:
We present a comparison of patient-reported outcomes
(PROMs) in relation to patient age, in patients who had received
a total (TKR) or unicompartmental knee replacement (UKR). The outcome
was evaluated using the Oxford knee score (OKS), EuroQol (EQ-5D)
and satisfaction scores. Patients aged 65 to 84 years demonstrated
better pre-operative function scores than those aged <
65 years
(OKS, p = 0.03; EQ-5D, p = 0.048) and those aged
≥ 85 years (OKS, p = 0.03). Post-operative scores were comparable
across age groups, but a linear trend for greater post-operative
improvement in OKS and EQ-5D was seen with decreasing age (p <
0.033). The overall mean satisfaction score at six months was 84.9,
but those aged <
55 years exhibited a lower mean level of satisfaction (78.3)
compared with all other age groups (all p <
0.031). The cumulative
overall two-year revision rate was 1.3%. This study demonstrates
that good early outcomes, as measured by the OKS and EQ-5D, can
be anticipated following knee replacement regardless of the patient’s
age, although younger patients gain greater improvement. However,
the lower satisfaction in those aged
<
55 years is a concern, and suggests that outcome is not fully
encapsulated by the OKS and EQ-5D evaluation, and raises the question
whether the OKS alone is an appropriate measure of pain and function
in younger, more active individuals. Cite this article:
Patella subluxation assessed on dynamic MRI has
previously been shown to be associated with anterior knee pain. In
this MRI study of 60 patients we investigated the relationship between
subluxation and multiple bony, cartilaginous and soft-tissue factors
that might predispose to subluxation using discriminant function
analysis. Patella engagement (% of patella cartilage overlapping with trochlea
cartilage) had the strongest relationship with subluxation. Patellae
with >
30% engagement tended not to sublux; those with <
30%
tended to sublux. Other factors that were associated with subluxation
included the tibial tubercle-trochlea notch distance, vastus medialis obliquus
distance from patella, patella alta, and the bony and cartilaginous
sulcus angles in the superior part of the trochlea. No relationship
was found between subluxation and sulcus angles for cartilage and
bone in the middle and lower part of the trochlea, cartilage thicknesses
and Wiberg classification of the patella. This study indicates that patella engagement is a key factor
associated with patellar subluxation. This suggests that in patients
with anterior knee pain with subluxation, resistant to conservative
management, surgery directed towards improving patella engagement
should be considered. A clinical trial is necessary to test this
hypothesis.
We have compared the outcome of hemiarthroplasty of the shoulder in three distinct diagnostic groups, using survival analysis as used by the United Kingdom national joint registers, patient-reported outcome measures (PROMs) as recommended by Darzi in the 2008 NHS review, and transition and satisfaction questions. A total of 72 hemiarthroplasties, 19 for primary osteoarthritis (OA) with an intact rotator cuff, 22 for OA with a torn rotator cuff, and 31 for rheumatoid arthritis (RA), were followed up for between three and eight years. All the patients survived, with no revisions or dislocations and no significant radiological evidence of loosening. The mean new Oxford shoulder score (minimum/worst 0, maximum/best 48) improved significantly for all groups (p <
0.001), in the OA group with an intact rotator cuff from 21.4 to 38.8 (effect size 2.9), in the OA group with a torn rotator cuff from 13.3 to 27.2 (effect size 2.1) and in the RA group from 13.7 to 28.0 (effect size 3.1). By this assessment, and for the survival analysis, there was no significant difference between the groups. However, when ratings using the patient satisfaction questions were analysed, eight (29.6%) of the RA group were ‘disappointed’, compared with one (9.1%) of the OA group with cuff intact and one (7.7%) of the OA group with cuff torn. All patients in the OA group with cuff torn indicated that they would undergo the operation again, compared to ten (90.9%) in the OA group with cuff intact and 20 (76.9%) in the RA group. The use of revision rates alone does not fully represent outcome after hemiarthroplasty of the shoulder. Data from PROMs provides more information about change in pain and the ability to undertake activities and perform tasks. The additional use of satisfaction ratings shows that both the rates of revision surgery and PROMs need careful interpretation in the context of patient expectations.
Using the General Practice Research Database, we examined the temporal changes in the rates of primary total hip (THR) and total knee (TKR) replacement, the age at operation and the female-to-male ratio between 1991 and 2006 in the United Kingdom. We identified 27 113 patients with THR and 23 843 with TKR. The rate of performance of THR and TKR had increased significantly (p <
0.0001 for both) during the 16-year period and was greater for TKR, especially in the last five years. The mean age at operation was greater for women than for men and had remained stable throughout the period of study. The female-to-male ratio was higher for THR and TKR and had remained stable. The data support the notion that the rate of joint replacement is increasing in the United Kingdom with the rate of TKR rising at the highest rate. The perception that the mean age for TKR has decreased over time is not supported.
Inflammatory pseudotumours occasionally occur after metal-on-metal hip resurfacing and often lead to revision. Our aim was to determine the severity of this complication by assessing the outcome of revision in these circumstances and by comparing this with the outcome of other metal-on-metal hip resurfacing revisions as well as that of matched primary total hip replacements. We identified 53 hips which had undergone metal-on-metal hip resurfacing and required revision at a mean of 1.59 years (0.01 to 6.69) after operation. Of these, 16 were revised for pseudotumours, 21 for fracture and 16 for other reasons. These were matched by age, gender and diagnosis with 103 patients undergoing primary total hip replacement with the Exeter implant. At a mean follow-up of three years (0.8 to 7.2) the outcome of metal-on-metal hip resurfacing revision for pseudotumour was poor with a mean Oxford hip score of 20.9 ( The outcome of revision for pseudotumour is poor and consideration should be given to early revision to limit the extent of the soft-tissue destruction. The outcome of resurfacing revision for other causes is good.
Balancing service provision and surgical training is a challenging issue that affects all healthcare systems. A multicentre prospective study of 1501 total hip replacements was undertaken to investigate whether there is an association between surgical outcome and the grade of the operating surgeon, and whether there is any difference in outcome if surgeons’ assistants assist with the operation, rather than orthopaedic trainees. The primary outcome measure was the change in the Oxford hip score (OHS) at five years. Secondary outcomes included the rate of revision and dislocation, operating time, and length of hospital stay. There was no significant difference in ΔOHS or complication rates between operations undertaken by trainers and trainees, or those at which surgeons’ assistants and trainees were the assistant. However, there was a significant difference in the duration of surgery, with a mean reduction of 28 minutes in those in which a surgeons’ assistant was the assistant. This study provides evidence that total hip replacements can be performed safely and effectively by appropriately trained surgeons in training, and that there are potential benefits of using surgeons’ assistants in orthopaedic surgery.
We randomised 62 knees to receive either cemented or cementless versions of the Oxford unicompartmental knee replacement. The implants used in both arms of the study were similar, except that the cementless components were coated with porous titanium and hydroxyapatite. The tibial interfaces were studied with fluoroscopically-aligned radiographs. At one year there was no difference in clinical outcome between the two groups. Narrow radiolucent lines were seen at the bone-implant interfaces in 75% of cemented tibial components. These were partial in 43%, and complete in 32%. In the cementless implants, partial radiolucencies were seen in 7% and complete radiolucencies in none. These differences are statistically significant (p <
0.0001) and imply satisfactory bone ingrowth into the cementless implants.
A prospective, multi-centre study was carried out on 1421 total hip replacements between January 1999 and July 2007 to examine if obesity has an effect on clinical outcomes. The patients were categorised into three groups: non-obese (body mass index (BMI) <
30 kg/m2), obese (BMI 30 to 40 kg/m2) and morbidly obese (BMI >
40 kg/m2). The primary outcome measure was the change in Oxford hip score at five years. Secondary outcome measures included dislocation and revision rates, increased haemorrhage, deep infection, deep-vein thrombosis and pulmonary embolism, mean operating time and length of hospital stay. Radiological analysis assessing heterotopic ossification, femoral osteolysis and femoral stem positioning was performed. Data were incomplete for 362 hips (25.5%) There was no difference in the change in the Oxford hip score, complication rates or radiological changes at five years between the groups. The morbidly obese group was significantly younger and required a significantly longer operating time. Obese and morbidly obese patients have as much to gain from total hip replacement as non-obese patients.
Few independent studies have reported the outcome of resurfacing arthroplasty of the hip. The aim of this study was to report the five-year clinical outcome and seven-year survival of an independent series. A total of 610 Birmingham Hip Resurfacing arthroplasties were performed in 532 patients with a mean age of 51.8 years (16.5 to 81.6). They were followed for between two and eight years; 107 patients (120 hips) had been followed up for more than five years. Two patients were lost to follow-up. At a minimum of five years’ follow-up, 79 of 85 hips (93%) had an excellent or good outcome according to the Harris hip score. The mean Oxford hip score was 16.1 points ( Considering that these patients are young and active these results are good, and support the use of resurfacing. Further study is needed to address the early failures, particularly those related to fracture and metal debris.
Patellofemoral joint degeneration is often considered a contraindication to medial unicompartmental knee replacement. We examined the validity of this preconception using information gathered prospectively on the intra-operative status of the patellofemoral joint in 824 knees in 793 consecutive patients who underwent Oxford unicondylar knee replacement for anteromedial osteoarthritis. All operations were performed between January 1998 and September 2005. A five-point grading system classified degeneration of the patellofemoral joint from none to full-thickness cartilage loss. A subclassification of the presence or absence of any full-thickness cartilage loss was subsequently performed to test selected hypotheses. Outcome was evaluated independently by physiotherapists using the Oxford and the American Knee Society Scores with a minimum follow-up of one year. Full-thickness cartilage loss on the trochlear surface was observed in 100 of 785 knees (13%), on the medial facet of the patella in 69 of 782 knees (9%) and on the lateral facet in 29 of 784 knees (4%). Full-thickness cartilage loss at any location was seen in 128 knees (16%) and did not produce a significantly worse outcome than those with a normal or near-normal joint surface. The severity of the degeneration at any of the intra-articular locations also had no influence on outcome. We concluded that, provided there is not bone loss and grooving of the lateral facet, damage to the articular cartilage of the patellofemoral joint to the extent of full-thickness cartilage loss is not a contraindication to the Oxford mobile-bearing unicompartmental knee replacement.
Anterior knee pain and/or radiological evidence of degeneration of the patellofemoral joint are considered to be contraindications to unicompartmental knee replacement. The aim of this study was to determine whether this is the case. Between January 2000 and September 2003, in 100 knees (91 patients) in which Oxford unicompartmental knee replacements were undertaken for anteromedial osteoarthritis, pre-operative anterior knee pain and the radiological status of the patellofemoral joint were defined using the Altman and Ahlback systems. Outcome was evaluated at two years with the Oxford knee score and the American Knee Society score. Pre-operatively 54 knees (54%) had anterior knee pain. The clinical outcome was independent of the presence or absence of pre-operative anterior knee pain. Degenerative changes of the patellofemoral joint were seen in 54 patients (54%) on the skyline radiographs, including ten knees (10%) with joint space obliteration. Patients with medial patellofemoral degeneration had a similar outcome to those without. For some outcome measures patients with lateral patellofemoral degeneration had a worse score than those without, but these patients still had a good outcome, with a mean Oxford knee score of 37.6 (SD 9.5). These results show that neither anterior knee pain nor radiologically-demonstrated medial patellofemoral joint degeneration should be considered a contraindication to Oxford unicompartmental knee replacement. With lateral patellofemoral degeneration the situation is less well defined and caution should be observed.
The Oxford hip and knee scores have been extensively used since they were first described in 1996 and 1998. During this time, they have been modified and used for many different purposes. This paper describes how they should be used and seeks to clarify areas of confusion.
The options for treatment of the young active patient with isolated symptomatic osteoarthritis of the medial compartment and pre-existing deficiency of the anterior cruciate ligament are limited. The potential longevity of the implant and levels of activity of the patient may preclude total knee replacement, and tibial osteotomy and unicompartmental knee arthroplasty are unreliable because of the ligamentous instability. Unicompartmental knee arthroplasties tend to fail because of wear or tibial loosening resulting from eccentric loading. Therefore, we combined reconstruction of the anterior cruciate ligament with unicompartmental arthroplasty of the knee in 15 patients (ACLR group), and matched them with 15 patients who had undergone Oxford unicompartmental knee arthroplasty with an intact anterior cruciate ligament (ACLI group). The clinical and radiological data at a minimum of 2.5 years were compared for both groups. The groups were well matched for age, gender and length of follow-up and had no significant differences in their pre-operative scores. At the last follow-up, the mean outcome scores for both the ACLR and ACLI groups were high (Oxford knee scores of 46 (37 to 48) and 43 (38 to 46), respectively, objective Knee Society scores of 99 (95 to 100) and 94 (82 to 100), and functional Knee Society scores of 96 and 96 (both 85 to 100). One patient in the ACLR group needed revision to a total knee replacement because of infection. No patient in either group had radiological evidence of component loosening. The radiological study showed no difference in the pattern of tibial loading between the groups. The short-term clinical results of combined anterior cruciate ligament reconstruction and unicompartmental knee arthroplasty are excellent. The previous shortcomings of unicompartmental knee arthroplasty in the presence of deficiency of the anterior cruciate ligament appear to have been addressed with the combined procedure. This operation seems to be a viable treatment option for young active patients with symptomatic arthritis of the medial compartment, in whom the anterior cruciate ligament has been ruptured.
We performed a clinical and radiological study to determine the rate of failure of the Charnley Elite-Plus femoral component. Our aim was to confirm or refute the predictions of a previous roentgen stereophotogrammetric analysis study in which 20% of the Charnley Elite-Plus stems had shown rapid posterior head migration. It was predicted that this device would have a high early rate of failure. We examined 118 patients at a mean of nine years after hip replacement, including the 19 patients from the original roentgen stereophotogrammetric study. The number of revision procedures was recorded and clinical and radiological examinations were performed. The rate of survival of the femoral stems at ten years was 83% when revision alone was considered to be a failure. It decreased to 59% when a radiologically loose stem was also considered to be a failure. All the patients previously shown in the roentgen stereophotogrammetric study to have high posterior head migration went on to failure. There was a highly significant difference (p = 0.002) in posterior head migration measured at two years after operation between failed and non-failed femoral stems, but there was no significant difference in subsidence between these two groups. Our study has shown that the Charnley Elite-Plus femoral component has an unacceptably high rate of failure. It confirms that early evaluation of new components is important and that roentgen stereophotogrammetric is a good tool for this. Our findings have also shown that rapid posterior head migration is predictive of premature loosening and a better predictor than subsidence.
We inserted an electrode up the femoral neck into the femoral head of ten patients undergoing a metal-on-metal hip resurfacing arthroplasty through a posterior surgical approach and measured the oxygen concentration during the operation. In every patient the blood flow was compromised during surgery, but the extent varied. In three patients, the oxygen concentration was zero at the end of the procedure. The surgical approach caused a mean 60% drop (p <
0.005) in oxygen concentration while component insertion led to a further 20% drop (p <
0.04). The oxygen concentration did not improve significantly on wound closure. This study demonstrates that during hip resurfacing arthroplasty, patients experience some compromise to their femoral head blood supply and some have complete disruption.
Abnormal sagittal kinematics after total knee replacement (TKR) can adversely affect functional outcome. Two important determinants of knee kinematics are component geometry and the presence or absence of a posterior-stabilising mechanism (cam-post). We investigated the influence of these variables by comparing the kinematics of a TKR with a polyradial femur with a single radius design, both with and without a cam-post mechanism. We assessed 55 patients, subdivided into four groups, who had undergone a TKR one year earlier by using an established fluoroscopy protocol in order to examine their kinematics
Polished, tapered stems are now widely used for cemented total hip replacement and many such designs have been introduced. However, a change in stem geometry may have a profound influence on stability. Stems with a wide, rectangular proximal section may be more stable than those which are narrower proximally. We examined the influence of proximal geometry on stability by comparing the two-year migration of the Exeter stem with a more recent design, the CPS-Plus, which has a wider shoulder and a more rectangular cross-section. The hypothesis was that these design features would increase rotational stability. Both stems subsided approximately 1 mm relative to the femur during the first two years after implantation. The Exeter stem was found to rotate into valgus (mean 0.2°,
When the Oxford unicompartmental meniscal bearing arthroplasty is used in the lateral compartment of the knee, 10% of the bearings dislocate. A radiological review was carried out to establish if dislocation was related to surgical technique. The postoperative radiographs of 46 lateral unicompartmental arthroplasties were analysed. Five variables which related to the position and alignment of the components were measured. Dislocations occurred in six knees. Only one of the five variables, the proximal tibial varus angle, had a statistically significant relationship to dislocation. This variable quantifies the height of the lateral joint line. The mean proximal tibial varus angle for knees the bearings of which had dislocated was 9° and for those which had not it was 5°. In both groups it was greater than would be expected in the normal knee (3°). Our study suggests that a high proximal tibial varus angle is associated with dislocation. The surgical technique should be modified to account for this, with care being taken to avoid damage to or over-distraction of the lateral soft tissues.
We have assessed the effectiveness of reconstruction of the anterior cruciate ligament (ACL) in reducing functional tibial translation (TT). The gait of 11 ACL-deficient patients was studied using Vicon equipment before and after surgery. Measurements of the angle between the patellar tendon and the long axis of the tibia were obtained in order to calculate TT in the sagittal plane relative to the uninjured limb during standing and walking. Before surgery, patients did not show abnormal TT on the injured side, but after surgery significant anterior TT was found in the operated limb for every parameter of gait. Abnormal anterior TT occurring during activity does not seem to be reduced by reconstruction; rather, it increases. It may be that the increased translation results from relaxation of excess contraction of the hamstring muscles, since compensatory muscle activity no longer is required in a reconstructed knee. The reduction of TT may not be an appropriate objective in surgery on the ACL.