Aims. The aim of this independent multicentre study was to assess the mid-term results of mobile bearing unicondylar knee arthroplasty (UKA) for isolated lateral osteoarthritis of the knee joint. Patients and Methods. We retrospectively evaluated 363 consecutive, lateral UKAs (346 patients) performed using the Oxford domed lateral prosthesis undertaken in three high-volume knee arthroplasty centres between 2006 and 2014. Mean age of the patients at surgery was 65 years (36 to 88) with a mean final follow-up of 37 months (12 to 93). Results. A total of 36 (10.5%) patients underwent revision surgery, giving a survival rate of 90.1% at three years (95% confidence intervals (CI) 86.1 to 93.1; number at risk: 155) and 85.0% at five years (95% CI 77.9 to 89.9; number at risk: 43). Dislocation of the mobile bearing occurred in 18 patients (5.6%) at three years (95% CI 1.0 to 16.4; number at risk: 154) and in 20 patients (8.5%) at five years (95% CI 1.0 to 27.0; number at risk: 42). There were no significant differences in the dislocation rate between the participating centres or the surgeons. We were not able to identify an effect of each surgeon’s learning curve on the dislocation rate of the mobile bearing. The clinical outcome in patients without revision surgery at final follow-up was good to excellent, with a mean Oxford knee score of 40.3 (95% CI 39.4 to 41.2), a mean Tegner activity score of 3.2 (95% CI 3.1 to 3.3) and a mean University of California, Los Angeles score of 5.7 (95% CI 5.5 to 5.9). Conclusion. Our data, which consists of a high number of patients treated with mobile bearing UKA in the lateral compartment, indicates a high revision rate of 15% at five years with dislocation of the mobile bearing being the main reason for implant failure. Despite the good functional and clinical results and the high patient satisfaction in our study group, we therefore discontinued using mobile-bearing lateral UKA in favour of a fixed-bearing component. Cite this article: Bone Joint J 2018;100-B:42–9

Mobile-bearing unicompartmental knee replacements (UKRs) with a flat tibial plateau have not performed well in the lateral compartment, owing to a high dislocation rate. This led to the development of the Domed Lateral Oxford UKR (Domed OUKR) with a biconcave bearing. The aim of this study was to assess the survival and clinical outcomes of the Domed OUKR in a large patient cohort in the medium term. We prospectively evaluated 265 consecutive knees with isolated disease of the lateral compartment and a mean age at surgery of 64 years (32 to 90). At a mean follow-up of four years (. sd. 2.2, (0.5 to 8.3)) the mean Oxford knee score was 40 out of 48 (. sd. 7.4). A total of 12 knees (4.5%) had re-operations, of which four (1.5%) were for dislocation. All dislocations occurred in the first two years. Two (0.8%) were secondary to significant trauma that resulted in ruptured ligaments, and two (0.8%) were spontaneous. In four patients (1.5%) the UKR was converted to a primary TKR. Survival at eight years, with failure defined as any revision, was 92.1% (95% confidence interval 81.3 to 100). . The Domed Lateral OUKR gives good clinical outcomes, low re-operation and revision rates and a low dislocation rate in patients with isolated lateral compartmental disease, in the hands of the designer surgeons. Cite this article: Bone Joint J 2014;96-B:59–64

Patellar instability most frequently presents during adolescence. Congenital and infantile dislocation of the patella is a distinct entity from adolescent instability and measurable abnormalities may be present at birth. In the normal patellofemoral joint an increase in quadriceps angle and patellar height are matched by an increase in trochlear depth as the joint matures. Adolescent instability may herald a lifelong condition leading to chronic disability and arthritis. Restoring normal anatomy by trochleoplasty, tibial tubercle transfer or medial patellofemoral ligament (MPFL) reconstruction in the young adult prevents further instability. Although these techniques are proven in the young adult, they may cause growth arrest and deformity where the physis is open. A vigorous non-operative strategy may permit delay of surgery until growth is complete. Where non-operative treatment has failed a modified MPFL reconstruction may be performed to maintain stability until physeal closure permits anatomical reconstruction. If significant growth remains an extraosseous reconstruction of the MPFL may impart the lowest risk to the physis. If minor growth remains image intensifier guided placement of femoral intraosseous fixation may impart a small, but acceptable, risk to the physis. This paper presents and discusses the literature relating to adolescent instability and provides a framework for management of these patients. Cite this article: Bone Joint J 2017;99-B:159–70

Injury to the common peroneal nerve was present in 14 of 55 patients (25%) with dislocation of the knee. All underwent ligament reconstruction. The most common presenting direction of the dislocation was anterior or anteromedial with associated disruption of both cruciate ligaments and the posterolateral structures of the knee. Palsy of the common peroneal nerve was present in 14 of 34 (41%) of these patients. Complete rupture of the nerve was seen in four patients and a lesion in continuity in ten. Three patients with lesions in continuity, but with less than 7 cm of the nerve involved, had complete recovery within six to 18 months. In the remaining seven with more extensive lesions, two regained no motor function, and one had only MRC grade-2 function. Four patients regained some weak dorsiflexion or eversion (MRC grade 3 or 4). Some sensory recovery occurred in all seven of these patients, but was incomplete. In summary, complete recovery occurred in three (21%) and partial recovery of useful motor function in four (29%). In the other seven (50%) no useful motor or sensory function returned

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 investigated the three-dimensional morphological differences of the articular surface of the femoral trochlea in patients with recurrent dislocation of the patella and a normal control group using three-dimensional computer models. There were 12 patients (12 knees) and ten control subjects (ten knees). Three-dimensional computer models of the femur, including the articular cartilage, were created. Evaluation was performed on the shape of the articular surface, focused on its convexity, and the proximal and mediolateral distribution of the articular cartilage of the femoral trochlea. The extent of any convexity, and the proximal distribution of the articular cartilage, expressed as the height, were shown by the angles about the transepicondylar axis. The mediolateral distribution of the articular cartilage was assessed by the location of the medial and lateral borders of the articular cartilage. The mean extent of convexity was 24.9° . sd. 6.7° for patients and 11.9° . sd. 3.6° for the control group (p < 0.001). The mean height of the articular cartilage was 91.3° . sd. 8.3° for the patients and 83.3° . sd. 7.7° for the control group (p = 0.03), suggesting a wider convex trochlea in the patients with recurrent dislocation of the patella caused by the proximally-extended convex area. The lateral border of the articular cartilage of the trochlea in the patients was more laterally located than in the control group. Our findings therefore quantitatively demonstrated differences in the shape and distribution of the articular cartilage on the femoral trochlea between patients with dislocation of the patella and normal subjects

Trochlear dysplasia is a developmental condition characterised by an abnormally flat or dome-shaped trochlea and is an important contributory factor to patellofemoral instability and recurrent dislocation. We studied prospectively a series of 54 consecutive patients (59 knees) with patellofemoral instability secondary to trochlear dysplasia, who were treated by a trochleoplasty by a single surgeon between June 2002 and June 2007. Pre- and post-operative scores were assessed by the patients and a satisfaction questionnaire was completed. Of the 54 patients (59 knees) in the series, 39 (44 knees) were female and 15 (15 knees) were male. Their mean age at surgery was 21 years and 6 months (14 years 4 months to 33 years 11 months). In 40 patients (42 knees) the mean follow-up was for 24 months (12 to 58). One patient was unable to attend for follow-up. An analysis of the results of those patients followed up for at least 12 months showed a statistically significant improvement in outcome (p < 0.001 for all scores). Overall, 50 patients (92.6%) were satisfied with the outcome of their procedure. The early results of trochleoplasty are encouraging in this challenging group of patients

We treated 21 patients with 22 dislocations of the knee by repair or reconstruction of all injured ligaments. Eight knees were treated in the acute phase (less than two weeks after injury); the remainder were treated more than six months after injury (6 to 72). Reconstructions were carried out with a combination of autograft and allograft tendons and by direct ligament repair where possible. At a mean follow-up of 32 months (11 to 77) the mean Lysholm score was 87 (81 to 91) in the acute group and 75 (53 to 100) in the delayed group. The mean Tegner activity rating was 5 in the acute group and 4.4 in the delayed group. The International Knee Documentation Committee assessment revealed no differences between the two groups. Instrumented testing of knee stability indicated better results for anterior cruciate ligament reconstructions which had been undertaken in the acute phase, but no difference in the outcome of posterior cruciate ligament reconstructions. There was no difference in the loss of knee movement between the two groups. Although the differences were small, the outcome in terms of overall knee function, activity levels and anterior tibial translation were better in those knees which had been reconstructed within two weeks of injury

We examined an39 patients (45 knees) who had undergone Elmslie-Trillat procedure for recurrent or habitual dislocation of the patella with a follow-up of more than ten years. The mean age at the time of surgery was 18.4 years; the mean follow-up was 161 months (120 to 238). Using Fulkerson’s functional knee score, 41 knees (91%) had an excellent or good result at a mean follow-up of 45 months, and this was maintained in 29 (64%) at the final review. The main cause of deterioration in the clinical results was the onset or worsening of patellofemoral joint pain, not patellar instability

The management of traumatic dislocation of the knee in 40 patients (41 knees) with a mean age of 26.3 years is described. They were treated by primary repair and reconstruction with autologous grafting of the anterior (ACL) and posterior cruciate ligaments (PCL) and repair injuries to the collateral ligament and soft-tissue. The ACL and PCL were reconstructed using the patellar tendon and the gracilis and semitendinosus tendons, respectively. Early mobilisation using a continuous-passive-movement machine and active exercises was started on the second day after operation. At a mean follow-up of 39 months no patient reported ‘giving way’ and all except one had good range of movement. Of the 41 knees, 21 were rated as excellent, 15 good, four fair and one poor. Early reconstruction of the cruciate ligaments and primary repair of the collateral ligaments followed by an aggressive rehabilitation programme are recommended for these young, active patients

Aims. The aim of this study was to examine the indications for further surgery and the characteristics of the patients within one year of medial unicompartmental knee arthroplasty (mUKA), providing an assessment of everyday clinical practice and outcomes in a high-volume country. Methods. All mUKAs which were performed between 1 April 2020 and 31 March 2021 and underwent further surgery within one year, from the Danish Knee Arthroplasty Registry (DKAR), were included. For primary procedures and reoperations, we received data on the characteristics of the patients, the indications for surgery, the type of procedure, and the sizes of the components individually, from each Danish private and public arthroplasty centre. All subsequent reoperations were recorded regardless of the time since the initial procedure. Results. A total of 2,431 primary mUKAs in 2,303 patients were reported to the DKAR during the study period and 55 patients (55 mUKAs; 2.3%; (95% CI 1.7 to 3.0)) underwent further surgery within one year. The most frequent indications for reoperation were periprosthetic fracture (n = 16; 0.7% (95% CI 0.4 to 1.1)), periprosthetic joint infection (PJI) (n = 13; 0.5% (95% CI 0.3 to 0.9)), and bearing dislocation (n = 9; 0.4% (95% CI 0.2 to 0.7)). Six periprosthetic fractures were treated with internal fixation, but five of these patients later underwent revision to a total knee arthroplasty (TKA). Ten PJIs were treated with debridement, antibiotics, and implant retention (DAIR). Due to persistent infection, four of these patients later underwent revision to a TKA. All nine bearing dislocations were treated with exchange of the liner, and seven occurred in patients who, based on their sex and height, probably had undersized femoral components. Conclusion. Reoperations are rare following mUKA in a high-volume country. The most frequent indications for further surgery were periprosthetic fracture, PJI, and bearing dislocation. Using internal fixation to treat periprosthetic fractures after mUKA gives poor results. Whether DAIR is an appropriate form of treatment for PJI in mUKAs, and how to ensure the effective eradication of infection in these patients, remains uncertain. Undersizing the femoral component might increase the risk of bearing dislocation. Cite this article: Bone Joint J 2025;107-B(3):314–321

Aims. Unicompartmental knee arthroplasty (UKA) is one option in the treatment of isolated unicompartmental advanced osteoarthritis (OA). While long-term results exist for medial mobile-bearing (MB) UKA, evidence regarding lateral MB-UKA is still limited. The Oxford Domed Lateral (ODL) implant aims to reduce the bearing dislocation rate in lateral MB-UKA through enhanced bearing entrapment. However, the long-term performance of this implant remains unclear. This study evaluated the long-term survival and clinical outcomes of the ODL in a non-designer centre. Methods. This single-centre retrospective analysis included 115 lateral MB-UKAs using the ODL performed between January 2006 and December 2014. The primary endpoint of the study was implant survival, defined as the time until a revision procedure was required for any reason. Secondary outcomes included Oxford Knee Score (OKS), Forgotten Joint Score (FJS), pain, satisfaction, and Tegner Activity Scale (TAS). Survival was assessed using Kaplan-Meier analysis. Results. At ten years, the cumulative implant survival rate was 74.8% (95% CI 65.2 to 82.1; number at risk = 71), with bearing dislocation (8.5%) and OA progression (10.4%) as leading revision causes. In 55 non-revised knees with a mean follow-up of 13.4 years (SD 1.8), the mean postoperative OKS improved significantly to 37.8 (SD 9.1) (p < 0.001). Additionally, 85.5% of patients (n = 47) reported satisfaction, with a mean FJS of 65.9 (SD 32.2) and TAS of 2.8 (SD 1.1). However, only 76.4% (n = 42) attained the patient-acceptable symptom state for OKS and FJS. Conclusion. This is the first long-term ODL study from a non-designer centre; our results demonstrated high failure rates due to bearing dislocation and OA progression, despite satisfactory clinical outcomes in non-revised patients. The disproportionately high risk of failure suggests that the MB design should be abandoned in favour of a fixed-bearing device for lateral UKA. Cite this article: Bone Joint J 2025;107-B(3):322–328

Aims. The optimal bearing surface design for medial unicompartmental knee arthroplasty (UKA) remains controversial. The aim of this study was to compare outcomes of fixed-bearing (FB) and mobile-bearing (MB) UKAs from a single high-volume institution. Methods. Prospectively collected data were reviewed for all primary cemented medial UKAs performed by seven surgeons from January 2006 to December 2022. A total of 2,999 UKAs were identified, including 2,315 FB and 684 MB cases. The primary outcome measure was implant survival. Secondary outcomes included 90-day and cumulative complications, reoperations, component revisions, conversion arthroplasties, range of motion, and patient-reported outcome measures. Overall mean age at surgery was 65.7 years (32.9 to 94.3), 53.1% (1,593/2,999) of UKAs were implanted in female patients, and demographics between groups were similar (p > 0.05). The mean follow-up for all UKAs was 3.7 years (0.0 to 15.6). Results. Using revision for any reason as an endpoint, five-year survival for FB UKAs was 97.2% (95% CI 96.4 to 98.1) compared to 96.0% for MB (95% CI 94.1 to 97.9; p = 0.008). The FB group experienced fewer component revisions (14/2,315, 0.6% vs 12/684, 1.8%; p < 0.001) and conversion arthroplasties (38/2315, 1.6% vs 24/684, 3.5%; p < 0.001). A greater number of MB UKAs underwent revision due to osteoarthritis progression (FB = 21/2,315, 0.9% vs MB = 16/684, 2.3%; p = 0.003). In the MB group, 12 (1.8%) subjects experienced bearing dislocations which required revision surgery. There were 15 early periprosthetic tibia fractures (0.6%) in the FB group compared to 0 for MB (p = 0.035). Conclusion. In similar patient populations, FB UKAs demonstrated slightly higher survival than a commonly used MB design. Adverse event profiles differed by bearing type, with an increased risk of bearing dislocation and OA progression with MB designs, and early periprosthetic tibia fractures for FB designs. Cite this article: Bone Joint J 2024;106-B(9):916–923

Aims. Unicompartmental knee arthroplasty (UKA) has higher revision rates than total knee arthroplasty (TKA). As revision of UKA may be less technically demanding than revision TKA, UKA patients with poor functional outcomes may be more likely to be offered revision than TKA patients with similar outcomes. The aim of this study was to compare clinical thresholds for revisions between TKA and UKA using revision incidence and patient-reported outcomes, in a large, matched cohort at early, mid-, and late-term follow-up. Methods. Analyses were performed on propensity score-matched patient cohorts of TKAs and UKAs (2:1) registered in the New Zealand Joint Registry between 1 January 1999 and 31 December 2019 with an Oxford Knee Score (OKS) response at six months (n, TKA: 16,774; UKA: 8,387), five years (TKA: 6,718; UKA: 3,359), or ten years (TKA: 3,486; UKA: 1,743). Associations between OKS and revision within two years following the score were examined. Thresholds were compared using receiver operating characteristic analysis. Reasons for aseptic revision were compared using cumulative incidence with competing risk. Results. Fewer TKA patients with ‘poor’ outcomes (≤ 25) subsequently underwent revision compared with UKA at six months (5.1% vs 19.6%; p < 0.001), five years (4.3% vs 12.5%; p < 0.001), and ten years (6.4% vs 15.0%; p = 0.024). Compared with TKA, the relative risk for UKA was 2.5-times higher for ‘unknown’ reasons, bearing dislocations, and disease progression. Conclusion. Compared with TKA, more UKA patients with poor outcomes underwent revision from early to long-term follow-up, and were more likely to undergo revision for ‘unknown’ reasons, which suggest a lower clinical threshold for UKA. For UKA, revision risk was higher for bearing dislocations and disease progression. There is supporting evidence that the higher revision UKA rates are associated with lower clinical thresholds for revision and additional modes of failure. Cite this article: Bone Joint J 2023;105-B(3):269–276

Aims. To report mid- to long-term results of Oxford mobile bearing domed lateral unicompartmental knee arthroplasty (UKA), and determine the effect of potential contraindications on outcome. Methods. A total of 325 consecutive domed lateral UKAs undertaken for the recommended indications were included, and their functional and survival outcomes were assessed. The effects of age, weight, activity, and the presence of full-thickness erosions of cartilage in the patellofemoral joint on outcome were evaluated. Results. Median follow-up was seven years (3 to 14), and mean age at surgery was 65 years (39 to 90). Median Oxford Knee Score (OKS) was 43 (interquartile range (IQR) 37 to 47), with 260 (80%) achieving a good or excellent score (OKS > 34). Revisions occurred in 34 (10%); 14 (4%) were for dislocation, of which 12 had no recurrence following insertion of a new bearing, and 12 (4%) were revised for medial osteoarthritis (OA). Ten-year survival was 85% (95% confidence interval (CI) 79 to 90, at risk 72). Age, weight, activity, and patellofemoral erosions did not have a significant effect on the clinical outcome or survival. Conclusion. Domed lateral UKA provides a good alternative to total knee arthroplasty (TKA) in the management of lateral compartment OA. Although dislocation is relatively easy to treat successfully, the dislocation rate of 4% is high. It is recommended that the stability of the bearing is assessed intraoperatively. If the bearing can easily be displaced, the fixed rather than the mobile bearing version of the Oxford lateral tibial component should be inserted instead. Younger age, heavier weight, high activity, and patellofemoral erosions did not detrimentally affect outcome, so should not be considered contraindications. Cite this article: Bone Joint J 2020;102-B(8):1033–1040

Aims

The aim of this study was to establish consensus statements on the diagnosis, nonoperative management, and indications, if any, for medial patellofemoral complex (MPFC) repair in patients with patellar instability, using the modified Delphi approach.

Aims

The aim of this study was to establish consensus statements on medial patellofemoral ligament (MPFL) reconstruction, anteromedialization tibial tubercle osteotomy, trochleoplasty, and rehabilitation and return to sporting activity in patients with patellar instability, using the modified Delphi process.

Aims

To identify unanswered questions about the prevention, diagnosis, treatment, and rehabilitation and delivery of care of first-time soft-tissue knee injuries (ligament injuries, patella dislocations, meniscal injuries, and articular cartilage) in children (aged 12 years and older) and adults.

Aims

Periprosthetic joint infection (PJI) is a challenging complication of any arthroplasty procedure. We reviewed our use of static antibiotic-loaded cement spacers (ABLCSs) for staged management of PJI where segmental bone loss, ligamentous instability, or soft-tissue defects necessitate a static construct. We reviewed factors contributing to their failure and techniques to avoid these complications when using ABLCSs in this context.

Aims

This study compared patient-reported outcomes of three total knee arthroplasty (TKA) designs from one manufacturer: one cruciate-retaining (CR) design, and two cruciate-sacrificing designs, anterior-stabilized (AS) and posterior-stabilized (PS).