We have examined the differences in clinical outcome of total knee replacement (TKR) with and without patellar resurfacing in a prospective, randomised study of 181 osteoarthritic knees in 142 patients using the Profix total knee system which has a femoral component with features considered to be anatomical and a domed patellar implant. The procedures were carried out between February 1998 and November 2002. A total of 159 TKRs in 142 patients were available for review at a mean of four years (3 to 7). The patients and the clinical evaluator were blinded in this prospective study. Evaluation was undertaken annually by an independent observer using the knee pain scale and the Knee Society clinical rating system. Specific evaluation of anterior knee pain, stair-climbing and rising from a seated to a standing position was also undertaken. No benefit was shown of TKR with patellar resurfacing over that without resurfacing with respect to any of the measured outcomes. In 22 of 73 knees (30.1%) with and 18 of 86 knees (20.9%) without patellar resurfacing there was some degree of anterior knee pain (p = 0.183). No revisions related to the patellofemoral joint were performed in either group. Only one TKR in each group underwent a re-operation related to the patellofemoral joint. A significant association between knee flexion contracture and anterior knee pain was observed in those knees with patellar resurfacing (p = 0.006)

Aims

Anterior cruciate ligament (ACL) rupture commonly leads to post-traumatic osteoarthritis, regardless of surgical reconstruction. This study uses standing MRI to investigate changes in contact area, contact centroid location, and tibiofemoral alignment between ACL-injured knees and healthy controls, to examine the effect of ACL reconstruction on these parameters.

Aims

This study aimed to identify the tibial component and femoral component coronal angles (TCCAs and FCCAs), which concomitantly are associated with the best outcomes and survivorship in a cohort of fixed-bearing, cemented, medial unicompartmental knee arthroplasties (UKAs). We also investigated the potential two-way interactions between the TCCA and FCCA.

Aims

The aim of this study was to evaluate the long-term inducible displacement of cemented tibial components ten years after total knee arthroplasty (TKA).

Aims

The aim of this study was to compare the post-operative radiographic and clinical outcomes between kinematically and mechanically aligned total knee arthroplasties (TKAs).

Aims

Unicompartmental knee arthroplasty (UKA) has been successfully performed in the United States healthcare system on outpatients. Despite differences in healthcare structure and financial environment, we hypothesised that it would be feasible to replicate this success and perform UKA with safe day of surgery discharge within the NHS, in the United Kingdom. This has not been reported in any other United Kingdom centres.

The restoration of knee alignment is an important goal during total knee arthroplasty (TKA). In the past surgeons aimed to restore neutral limb alignment during surgery. However, previous studies have demonstrated alignment to be dynamic, varying depending on the position of the limb and the degree of weight-bearing, and between patients. We used a validated computer navigation system to measure the femorotibial mechanical angle (FTMA) in 264 knees in 77 male and 55 female healthy volunteers aged 18 to 35 years (mean 26.2). We found the mean supine alignment to be a varus angle of 1.2° (standard deviation (sd) 4), with few patients having neutral alignment. FTMA differs significantly between males and females (with a mean varus of 1.7° (sd 4) and 0.4° (sd 3.9), respectively; p = 0.008). It changes significantly with posture, the knee hyperextending by a mean of 5.6°, and coronal plane alignment becoming more varus by 2.2° (sd 3.6) on standing compared with supine.

Knee alignment is different in different individuals and is dynamic in nature, changing with different postures. This may have implications for the assessment of alignment in TKA, which is achieved in non-weight-bearing conditions and which may not represent the situation observed during weight-bearing.

Cite this article: Bone Joint J 2015; 97-B:498–502

The optimal timing of total knee replacement (TKR) in patients with osteoarthritis, in relation to the severity of disease, remains controversial. This prospective study was performed to investigate the effect of the severity of osteoarthritis and other commonly available pre- and post-operative clinical parameters on the clinical outcome in a consecutive series of cemented TKRs. A total of 176 patients who underwent unilateral TKR were included in the study. Their mean age was 68 years (39 to 91), 63 (36%) were male and 131 knees (74%) were classified as grade 4 on the Kellgren–Lawrence osteoarthritis scale. A total of 154 patients (87.5%) returned for clinical review 12 months post-operatively, at which time the outcome was assessed using the Knee Society score.

A low radiological severity of osteoarthritis was not associated with pain 12 months post-operatively. However, it was significantly associated with an inferior level of function (p = 0.007), implying the need for increased focus on all possible reasons for pain in the knee and the forms of conservative treatment which are available for patients with lower radiological severity of osteoarthritis.

Cite this article: Bone Joint J 2014; 96-B:1498–1502.

We studied whether the presence of lateral osteophytes on plain radiographs was a predictor for the quality of cartilage in the lateral compartment of patients with varus osteoarthritic of the knee (Kellgren and Lawrence grade 2 to 3).

The baseline MRIs of 344 patients from the Osteoarthritis Initiative (OAI) who had varus osteoarthritis (OA) of the knee on hip-knee-ankle radiographs were reviewed. Patients were categorised using the Osteoarthritis Research Society International (OARSI) osteophyte grading system into 174 patients with grade 0 (no osteophytes), 128 grade 1 (mild osteophytes), 28 grade 2 (moderate osteophytes) and 14 grade 3 (severe osteophytes) in the lateral compartment (tibia). All patients had Kellgren and Lawrence grade 2 or 3 arthritis of the medial compartment. The thickness and volume of the lateral cartilage and the percentage of full-thickness cartilage defects in the lateral compartment was analysed.

There was no difference in the cartilage thickness or cartilage volume between knees with osteophyte grades 0 to 3. The percentage of full-thickness cartilage defects on the tibial side increased from < 2% for grade 0 and 1 to 10% for grade 3.

The lateral compartment cartilage volume and thickness is not influenced by the presence of lateral compartment osteophytes in patients with varus OA of the knee. Large lateral compartment osteophytes (grade 3) increase the likelihood of full-thickness cartilage defects in the lateral compartment.

Cite this article: Bone Joint J 2015;97-B:1634–9.

The Q angle is an important determinant of patellar tracking, though its clinical relevance is debatable. One controversy centres around any possible differences in its value between men and women. The accepted, though unproven explanation, for the greater Q angle in women is that a woman has a wider pelvis. However, because of the long distance between the pelvis and patella, relative to the distance from the patella to the tibial tuberosity, large changes in the position of the anterior superior iliac spine are necessary to effect significant changes in the Q angle. In our study of 69 subjects, we did not find such large differences in the position of the anterior superior iliac spine, and found a mean difference of only 2.3° between the Q angles of men and women.

Furthermore, we found that men and women of equal height demonstrated similar Q angles, with taller people having slightly smaller Q angles. The slight difference in Q angles between men and women can be explained by the fact that men tend to be taller.

We retrospectively reviewed the records of 1150 computer-assisted total knee replacements and analysed the clinical and radiological outcomes of 45 knees that had arthritis with a pre-operative recurvatum deformity. The mean pre-operative hyperextension deformity of 11° (6° to 15°), as measured by navigation at the start of the operation, improved to a mean flexion deformity of 3.1° (0° to 7°) post-operatively. A total of 41 knees (91%) were managed using inserts ≤ 12.5 mm thick, and none had mediolateral laxity > 2 mm from a mechanical axis of 0° at the end of the surgery. At a mean follow-up of 26.4 months (13 to 48) there was significant improvement in the mean Knee Society, Oxford knee and Western Ontario and McMaster Universities Osteoarthritis Index scores compared with the pre-operative values. The mean knee flexion improved from 105° (80° to 125°) pre-operatively to 131° (120° to 145°), and none of the limbs had recurrent recurvatum.

These early results show that total knee replacement using computer navigation and an algorithmic approach for arthritic knees with a recurvatum deformity can give excellent radiological and functional outcomes without recurrent deformity.

Varus malalignment after total knee replacement is associated with a poor outcome. Our aim was to determine whether the same was true for medial unicompartmental knee replacement (UKR). The anatomical leg alignment was measured prospectively using a long-arm goniometer in 160 knees with an Oxford UKR. Patients were then grouped according to their mechanical leg alignment as neutral (5° to 10° of valgus), mild varus (0° to 4° of valgus) and marked varus (> 0° of varus). The groups were compared at five years in terms of absolute and change in the Oxford Knee score, American Knee Society score and the incidence of radiolucent lines.

Post-operatively, 29 (18%) patients had mild varus and 13 (8%) had marked varus. The mean American Knee Society score worsened significantly (p < 0.001) with increasing varus. This difference disappeared if a three-point deduction for each degree of malalignment was removed. No other score deteriorated with increasing varus, and the frequency of occurrence of radiolucent lines was the same in each group.

We therefore conclude that after Oxford UKR, about 25% of patients have varus alignment, but that this does not compromise their clinical or radiological outcome. Following UKR the deductions for malalignment in the American Knee Society score are not justified.

We assessed the reliability, accuracy and variability of closed-wedge high tibial osteotomy (HTO) using computer-assisted surgery compared to the conventional technique. A total of 50 closed-wedge HTO procedures were performed using the navigation system, and compared with 50 HTOs that had been performed with the conventional technique. In the navigation group, the mean mechanical axis prior to osteotomy was varus 8.2°, and the mean mechanical axis following fixation was valgus 3.6°. On the radiographs the mean pre-operative mechanical axis was varus 7.3°, and the mean post-operative mechanical axis was valgus 2.1°. There was a positive correlation between the measured data taken under navigation and by radiographs (r > 0.3, p < 0.05). The mean correction angle was significantly more accurate in the navigation group (p < 0.002). The variability of the correction was significantly lower in the navigation group (2.3° vs 3.7°, p = 0,012). We conclude that navigation provides reliable real-time intra-operative information, may increase accuracy, and improves the precision of a closed-wedge HTO.

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 in vivo. The kinematic profile was obtained by measuring the patellar tendon angle through the functional knee flexion range (0° to 90°) and the results compared with 14 normal knees. All designs of TKR had abnormal sagittal kinematics compared with the normal knee. There was a significant (p < 0.05) difference between those of the two TKRs near to full extension. The presence of the cam-post mechanism did not influence the kinematics for either TKR design. These differences suggest that surface geometry is a stronger determinant of kinematics than the presence or absence of a cam-post mechanism for these two designs. This may be because the cam-post mechanism is ineffective.