Background. Patellar dislocation is a serious complication leading to patient morbidity following total knee arthroplasty. The cause can be multifactorial. Extensor mechanism imbalance may be present and result from technical errors such as malrotation of the implants. Methods. We performed a retrospective study assessing the outcomes of revision surgery for patellar dislocation in patients with component malrotation in both primary and revision total knee arthroplasty. Patient demographics, etiology of dislocation, presurgical deformity, intraoperation component position, complications, reoperation and knee society scores were collected. Results. Twenty patients (twenty-one knees) were identified. The average time from primary arthroplasty to onset of dislocation was 33.6 months (SD, 44.4), and the average time from dislocation to revision was 3.38 months (SD, 2.81). Seventeen knees (80.1%) had internal rotation of the tibial component and 7 knees (33.3%) had combined internal rotation of both the femoral and tibial components. Sixteen knees (76.1%) were treated with a condylar constrained implant at the time of revision, and 5 knees were converted to a hinged prosthesis. The average follow-up time was 56 months. During this time, one patient (4.54%) had a recurrent dislocation episode, requiring further surgery. At final follow up, the mean knee society score for the patient cohort was 86.2. Conclusion. Revision total knee arthroplasty to treat patellar dislocation in patients with malrotated components was associated with high success rates. After revision surgery, patients had a low recurrence of patellar dislocation, low complication rates, and excellent functional outcomes. For figures, tables, or references, please contact authors directly

We investigated the clinical and radiological outcome of trochleaplasty for recurrent patellar dislocation in association with trochlear dysplasia in 38 consecutive patients (45 knees) with a mean follow-up of 8.3 years (4 to 14). None had recurrence of dislocation after trochleaplasty. Post-operatively, patellofemoral pain, present pre-operatively in only 35 knees, became worse in 15 (33.4%), remained unchanged in four (8.8%) and improved in 22 (49%). Four knees which had no pain pre-operatively (8.8%) continued to have no pain. A total of 33 knees were available for radiological assessment. Post-operatively, all but two knees (93.9%) had correction of trochlear dysplasia radiologically but degenerative changes of the patellofemoral joint developed in 30% (10) of the knees. We conclude that recurrent patellar dislocation associated with trochlear dysplasia can be treated successfully by trochleaplasty, but the impact on patellofemoral pain and the development of patellofemoral osteoarthritis is less predictable. Overall, subjective patient satisfaction with restored patellofemoral stability after trochleaplasty appeared to outweigh its possible sequelae

Abstract. Introduction. Fractures of the articular surface of the patella or the lateral femoral condyle usually occur following acute dislocation of the patella. This study looked at the radiological and functional outcomes of fixation of osteochondral fractures. Methods. Twenty-nine patients (18 male, 11 female) sustained osteochondral fractures of the knee following patellar dislocation. All patients had detailed radiographic imaging and MRI scan of the knee preoperatively. An arthroscopic assessment was done, followed by fixation using bio-absorbable pins or headless screws either arthroscopically or mini-open arthrotomy. VMO plication or MPFL repair were done if necessary. MRI scan was done at follow-up to assess for healing of the fixed fragment prior to patient discharge. Results. The mean age of the patients was 21 yrs (9–74), 11 had osteochondral fracture of the patella (38%), while 18 were from the lateral femoral condyle (62%). 13 patients needed additional VMO plication. Mean follow up period was 7.7 years (1 to 12 years). As per Tegner activity scale, all patients returned to their pre-injury activity level (Mean score 7) and sports. None of the patients had a further episode of patellar dislocation. Mean postoperative IKDC score was 86.5 (SD 17.3), Kujala was 91.1(SD 15.5) and Tegner- lysholm was 88.7 (SD 14.4). All patients had statistically significant (p < 0.05) improvement. Post-operative MRI scan showed satisfactory union in all cases (100%). Conclusion. It is extremely important to identify this group of injury and treat them early to have satisfactory knee function and avoid long term complications of arthritis

We retrospectively reviewed the operative treatment carried out between 1988 and 1994 of eight patients with habitual patellar dislocation. In four the condition was bilateral. All patients had recurrent dislocation with severe functional disability. The surgical technique involved distal advancement of the patella by complete mobilisation of the patellar tendon, lateral release and advancement of vastus medialis obliquus. The long-term results were assessed radiologically, clinically and functionally using the Lysholm knee score, by an independent observer. The mean age at operation was 10.3 years (7 to 14) with a mean follow-up of 13.5 years (11 to 16). One patient required revision. At the latest follow-up, all patellae were stable and knees functional with a mean Lysholm knee score of 98 points (95 to 100). In those aged younger than ten years at operation there was a statistically significant improvement in the sulcus angle at the latest follow-up (Student’s t-test, p = 0.001). Two patients developed asymptomatic patella infera as a late complication. This technique offers a satisfactory treatment for the immature patient presenting with habitual patellar dislocation associated with patella alta. If performed early, we believe that remodelling of the shallow trochlea may occur, adding intrinsic patellofemoral stability

We evaluated the outcome in a series of patients with recurrent patellar dislocation who had either medial transfer of the tibial tuberosity and lateral release or an isolated lateral release as the primary treatment. The decision to use one or other procedure was based on a pre-operative distance between the tibial tuberosity to the trochlear groove (TTTG) of less than 10 mm to include the tibial tuberosity transfer in addition to the lateral release. Between April 2002 and December 2006, 49 patients (63 knees) underwent one of these procedures. A total of 35 patients (46 knees) was evaluated at a mean of 38 months (13 to 71) post-operatively. Medial transfer of the tibial tuberosity was performed in 33 knees and isolated lateral release in the remaining 13. Evaluation included the International Knee Documentation Committee (IKDC), the Kujala and the Short-form 36 scores. From the tibial tuberosity group 23 knees also underwent radiological examination at follow-up. There were further episodes of patellar dislocation in six of the 46 knees available for review. Further dislocation was noted in five of 33 knees (15.2%) in the tibial tuberosity transfer group and in one of 13 knees (7.7%) in the lateral release group. The mean subjective IKDC score was 80.4 (. sd. 11.6), the mean Kujala score 88 (. sd. 8.2) and the mean objective IKDC score was 79% normal and 21% nearly normal. The mean post-operative TTTG distance in the tibial tuberosity transfer group was 8.9 mm (3.2 to 15.7) compared with the mean pre-operative value of 16.8 mm (12.2 to 24.4)

Aims

The Oswestry-Bristol Classification (OBC) was recently described as an MRI-based classification tool for the femoral trochlear. The authors demonstrated better inter- and intraobserver agreement compared to the Dejour classification. As the OBC could potentially provide a very useful MRI-based grading system for trochlear dysplasia, it was the aim to determine the inter- and intraobserver reliability of the classification system from the perspective of the non-founder.

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. Methods. The James Lind Alliance (JLA) methodology for Priority Setting Partnerships was followed. An initial survey invited patients and healthcare professionals from the UK to submit any uncertainties regarding soft-tissue knee injury prevention, diagnosis, treatment, and rehabilitation and delivery of care. Over 1,000 questions were received. From these, 74 questions (identifying common concerns) were formulated and checked against the best available evidence. An interim survey was then conducted and 27 questions were taken forward to the final workshop, held in January 2023, where they were discussed, ranked, and scored in multiple rounds of prioritization. This was conducted by healthcare professionals, patients, and carers. Results. The top ten included questions regarding prevention, diagnosis, treatment, and rehabilitation. The number one question was, ‘How urgently do soft-tissue knee injuries need to be treated for the best outcome?’. This reflects the concerns of patients, carers, and the wider multidisciplinary team. Conclusion. This validated process has generated ten important priorities for future soft-tissue knee injury research. These have been submitted to the National Institute for Health and Care Research. All 27 questions in the final workshop have been published on the JLA website. Cite this article: Bone Joint J 2024;106-B(3):232–239

Aims. The purpose of this study was to explore the correlation between femoral torsion and morphology of the distal femoral condyle in patients with trochlear dysplasia and lateral patellar instability. Methods. A total of 90 patients (64 female, 26 male; mean age 22.1 years (SD 7.2)) with lateral patellar dislocation and trochlear dysplasia who were awaiting surgical treatment between January 2015 and June 2019 were retrospectively analyzed. All patients underwent CT scans of the lower limb to assess the femoral torsion and morphology of the distal femur. The femoral torsion at various levels was assessed using the a) femoral anteversion angle (FAA), b) proximal and distal anteversion angle, c) angle of the proximal femoral axis-anatomical epicondylar axis (PFA-AEA), and d) angle of the AEA–posterior condylar line (AEA-PCL). Representative measurements of distal condylar length were taken and parameters using the ratios of the bianterior condyle, biposterior condyle, bicondyle, anterolateral condyle, and anteromedial condyle were calculated and correlated with reference to the AEA, using the Pearson Correlation coefficient. Results. The femoral torsion had a strong correlation with distal condylar morphology. The FAA was significantly correlated with the ratio of the bianterior condyle (r = 0.355; p = 0.009), the AEA-PCL angle (r = 0.340; p = 0.001) and the ratio of the anterolateral condyle and lateral condyle (ALC-LC) (r = 0.309; p = 0.014). The PFA-AEA angle was also significantly correlated with the ratio of the bianterior condyle (r = 0.319; p = 0.008), the AEA-PCL angle (r = 0.231; p = 0.031), and the ratio of ALC-LC (r = 0.261; p = 0.034). In addition, the bianterior condyle ratio showed a significant correlation with the biposterior condyle ratio (r = -0.324; p = 0.027) and the AEA-PCL angle (r = 0.342; p = 0.021). Conclusion. Increased femoral torsion correlated with a prominent anterolateral condyle and a shorter posterolateral condyle compared with the medial condyle. The deformities of the anterior and posterior condyles are combined deformities rather than being isolated and individual deformities in patients with trochlear dysplasia and patella instability. Cite this article: Bone Joint J 2020;102-B(7):868–873

Abstract. Introduction. The incidence of significant acute chondral injuries with patella dislocation is around 10–15%. It is accepted that chondral procedures should only be performed in the presence of joint stability. Methodology. Patients were identified from surgeon/hospital logs. Patient demographics, lesion size and location, surgical procedure, patient reported outcome measures, post-operative MR imaging and complications were recorded. PROMs and patient satisfaction was obtained. Results. 20 knees (18 patients) were included. Mean age was 18.6 years (range; 11–39) and the mean follow-up was 16.6 months (range; 2–70). The defect locations were the lateral femoral condyle (9/20; 45%), patella (9/20; 45%), medial femoral condyle (1/20; 5%) and the trochlea (1/20; 5%). The mean defect size was 2.6cm2. Twelve knees were treated with cartilage fixation, 5 with microfracture and 3 with OATS. At follow up, the overall mean Lysholm score was 77.4 (± 17.1) with no chondral regenerative procedure being statistically superior. There was no difference in Lysholm scores between those patients having acute medial patellofemoral ligament reconstruction versus medial soft tissue plication (p=0.59). Five (25%) knees required re-operation (one arthroscopic arthrolysis; one patella chondroplasty; two removal of loose bodies; one implant adjustment). Overall 90% responded as being satisfied with surgery. Conclusion. Our aggressive pathway to identify and treat acute cartilage defects with early operative intervention and patella stabilisation has shown high rates of satisfaction and Lysholm scores with no major revisions. The full range of chondral restoration options should be considered by surgeons managing these patients

Aims. The aim of this study was to evaluate cartilaginous patellotrochlear congruence and patellofemoral alignment parameters after deepening trochleoplasty in severe trochlear dysplasia. Patients and Methods. The study group comprised 20 patients (two male, 18 female; mean age 24 years (16 to 39)) who underwent deepening trochleoplasty and medial patellofemoral ligament (MPFL) reconstruction for the treatment of recurrent lateral patellar dislocation due to severe trochlear dysplasia (Dejour type B to D). Pre- and postoperative MRI investigations of the study group were compared with MRI data of 20 age- and gender-matched control patients (two male, 18 female; mean age 27 years (18 to 44)) regarding the patellotrochlear contact ratio, patellotrochlear contact area, posterior patellar edge-trochlear groove ratio, and patellar tilt. Results. Preoperatively, all parameters in the study group indicated significant patellar malalignment, including a reduced patellotrochlear contact ratio (mean 0.38 (0.13 to 0.59) vs mean 0.67 (0.48 to 0.88); p < 0.001), reduced contact area (mean 128 mm. 2. (87 to 190) vs mean 183 mm. 2. (155 to 227); p < 0.001), increased patellar lateralization (mean 0.82 (0.55 to 1.0) vs mean 0.99 (0.93 to 1.1); p < 0.001) and increased patellar tilt (mean 25.8° (8.1° to 43.0°) vs mean 9.1° (0.5° to 16.8°); p < 0.001). Postoperatively, all parameters in the study group improved significantly and reached normal values compared with the control group. The patellotrochlear contact ratio increased to a mean of 0.63 (0.38 to 0.85) (p < 0.001), the contact area increased to a mean of 187 mm. 2. (101 to 255) (p < 0.001), the posterior patellar edge-trochlear groove ratio improved to a mean of 0.96 (0.83 to 0.91) (p < 0.001), and the patellar tilt decreased to a mean of 13.9° (8.1° to 22.1°) (p < 0.001) postoperatively. Conclusion. Deepening trochleoplasty and MPFL reconstruction normalized the patellotrochlear congruence and patellofemoral alignment parameters. Modifying the dysplastic trochlea involves approximating the trochlear morphology to the shape of the patella rather than inducing a patella and trochlea mismatch. Cite this article: Bone Joint J 2019;101-B:325–330

The management of osteoarthritis of the knee associated with patellar instability secondary to external tibial torsion > 45° is challenging. Patellofemoral biomechanics in these patients cannot be achieved by intra-articular correction using standard techniques of total knee replacement. We reviewed seven patients (eight knees) with recurrent patellar dislocation and one with bilateral irreducible lateral dislocation who had undergone simultaneous total knee replacement and internal tibial derotational osteotomy. All had osteoarthritis and severe external tibial torsion. The mean follow-up was for 47.2 months (24 to 120). The mean objective and functional Knee Society scores improved significantly (p = 0.0001) from 29.7 and 41.5 pre-operatively to 71.4 and 73.5 post-operatively, respectively. In all patients the osteotomies healed and patellar stability was restored. Excessive external tibial torsion should be identified and corrected in patients with osteoarthritis and patellar instability. Simultaneous internal rotation osteotomy of the tibia and total knee replacement is a technically demanding but effective treatment for such patients

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.

Purpose. Investigate the functional outcome of medial patellofemoral ligament (MPFL) surgery for patella instability. Compare functional outcome of direct MPFL repair and reconstruction using hamstring graft. Methods. All patients that underwent MPFL surgery for patella instability between 2007-2010 were retrospectively identified from operative records. Patients were divided based on whether they underwent direct repair of MPFL, or reconstruction using hamstring graft. The Kujala scoring questionnaire for patellofemoral disorders (max score 100) was used to assess their functional outcome following surgery. Results. 33 patients were identified, 11 were not suitable for inclusion in the study. The remaining 22 patients had a total of 25 operations for patella stabilisation (3 bilateral). Average age of patient at time of surgery was 21 (15-33), 15 male and 7 female. 17 had direct repair of MPFL, 8 had reconstruction using hamstring graft. Of the 8 reconstructions 6 were primary procedures and 2 were for failed direct repair due to further traumatic injury. Mean follow-up period was 17 months (6-43). Mean Kujala score overall 91.6, mean score for reconstruction group 93.2, direct repair score 90.7. Total number of further patella dislocations in the repair group was 1/17 (5.9%). No patients in the reconstruction group reported any further patella dislocations following their surgery. Conclusion. Both direct repair and reconstruction of MPFL for patella instability demonstrate high functional outcome at short/mid-term follow up. Our high success rate in direct MPFL repair, good functional outcome and low re-dislocation rate is better than that quoted in the current literature

An increased tibial tubercle–trochlear groove (TT-TG) distance is related to patellar maltracking and instability. Tibial tubercle transfer is a common treatment option for these patients with good short-term results, although the results can deteriorate over time owing to the progression of osteoarthritis. We present a ten-year follow-up study of a self-centring tibial tubercle osteotomy in 60 knees, 30 with maltracking and 30 with patellar instability. Inclusion criteria were a TT-TG ≥ 15 mm and symptoms for > one year. One patient (one knee) was lost to follow-up and one required total knee arthroplasty because of progressive osteoarthritis. Further patellar dislocations occurred in three knees, all in the instability group, one of which required further surgery. The mean visual analogue scores for pain, and Lysholm and Kujala scores improved significantly and were maintained at the final follow-up (repeated measures, p = 0.000, intergroup differences p = 0.449). Signs of maltracking were found in only a minority of patients, with no difference between groups (p > 0.05). An increase in patellofemoral osteoarthritis was seen in 16 knees (31%) with a maximum of grade 2 on the Kellgren–Lawrence scale. The mean increase in grades was 0.31 (0 to 2) and 0.41 (0 to 2) in the maltracking and instability groups respectively (p = 0.2285). This self-centring tibial tubercle osteotomy provides good results at ten years’ follow-up without inducing progressive osteoarthritis. Cite this article: Bone Joint J 2015;97-B:329–36

An abnormal lateral position of the tibial tuberosity causes distal malalignment of the extensor mechanism of the knee and can lead to lateral tracking of the patella causing anterior knee pain or objective patellar instability, characterised by recurrent dislocation. Computer tomography is used for a precise pre-operative assessment of the tibial tubercle-trochlear groove distance. A distance of more than 15 mm is considered to be pathological and an indication for surgery in symptomatic patients. In a prospective study we performed a subtle transfer of the tibial tuberosity according to the information gained from the pre-operative CT scan. This method was applied to two groups of patients, those with painful lateral tracking of the patella, and those with objective patellar instability. We evaluated the clinical results in 30 patients in each group. The outcome was documented at 3, 12 and 24 months using the Lysholm scale, the Kujala score, and a visual analogue pain score. Post-operatively, all but one patient in the instability group who had a patellar dislocation requiring further surgery reported good improvement with no further subluxation or dislocation. All patients in both groups had a marked improvement in pain and functional score. Two patients sustained a tibial fracture six and seven weeks after surgery. One patient suffered a per-operative fracture of the tibial tubercle which later required further fixation. If carefully performed, this type of transfer of the tibial tubercle appears to be a satisfactory technique for the treatment of patients with an increased tibial tubercle-trochlear groove distance and who present with symptoms related to lateral maltracking of the patella

Aims

The aim of this study was to evaluate medium- to long-term outcomes and complications of the Stanmore Modular Individualised Lower Extremity System (SMILES) rotating hinge implant in revision total knee arthroplasty (rTKA) at a tertiary unit. It is hypothesized that this fully cemented construct leads to satisfactory clinical outcomes.

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

With up to 40% of patients having patellofemoral joint osteoarthritis (PFJ OA), the two arthroplasty options are to replace solely the patellofemoral joint via patellofemoral arthroplasty (PFA), or the entire knee via total knee arthroplasty (TKA). The aim of this study was to assess postoperative success of second-generation PFAs compared to TKAs for patients treated for PFJ OA using patient-reported outcome measures (PROMs) and domains deemed important by patients following a patient and public involvement meeting.

Aims

This study aims to identify the top unanswered research priorities in the field of knee surgery using consensus-based methodology.

We used three-dimensional movement analysis by computer modelling of knee flexion from 0° to 50° in 14 knees in 12 patients with recurrent patellar dislocation and in 15 knees in ten normal control subjects to compare the in vivo three-dimensional movement of the patella. Flexion, tilt and spin of the patella were described in terms of rotation angles from 0°. The location of the patella and the tibial tubercle were evaluated using parameters expressed as percentage patellar shift and percentage tubercle shift. Patellar inclination to the femur was also measured and patellofemoral contact was qualitatively and quantitatively analysed. The patients had greater values of spin from 20° to 50°, while there were no statistically significant differences in flexion and tilt. The patients also had greater percentage patellar shift from 0° to 50°, percentage tubercle shift at 0° and 10° and patellar inclination from 0° to 50° with a smaller oval-shaped contact area from 20° to 50° moving downwards on the lateral facet. Patellar movement analysis using a three-dimensional computer model is useful to clearly demonstrate differences between patients with recurrent dislocation of the patella and normal control subjects