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

Alternative alignment concepts, including kinematic and restricted kinematic, have been introduced to help improve clinical outcomes following total knee arthroplasty (TKA). The purpose of this study was to evaluate the clinical results, along with patient satisfaction, following TKA using the concept of restricted kinematic alignment.

Aims

The aim of this study was to evaluate cartilaginous patellotrochlear congruence and patellofemoral alignment parameters after deepening trochleoplasty in severe trochlear dysplasia.

Aims

The results of kinematic total knee arthroplasty (KTKA) have been reported in terms of limb and component alignment parameters but not in terms of gap laxities and differentials. In kinematic alignment (KA), balance should reflect the asymmetrical balance of the normal knee, not the classic rectangular flexion and extension gaps sought with gap-balanced mechanical axis total knee arthroplasty (MATKA). This paper aims to address the following questions: 1) what factors determine coronal joint congruence as measured on standing radiographs?; 2) is flexion gap asymmetry produced with KA?; 3) does lateral flexion gap laxity affect outcomes?; 4) is lateral flexion gap laxity associated with lateral extension gap laxity?; and 5) can consistent ligament balance be produced without releases?

Aims

Guided growth using eight-plates is commonly used for correction of angular limb deformities in growing children. The principle is of tethering at the physeal periphery while enabling growth in the rest of the physis. The method is also applied for epiphysiodesis to correct limb-length discrepancy (LLD). Concerns have been raised regarding the potential of this method to create an epiphyseal deformity. However, this has not been investigated. The purpose of this study was to detect and quantify the occurrence of deformities in the proximal tibial epiphysis following treatment with eight-plates.

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.

Aims

The aim of this study was to investigate the changes in femoral trochlear morphology following surgical correction of recurrent patellar dislocation associated with trochlear dysplasia in children.

The efficacy of circumpatellar electrocautery in reducing the incidence of post-operative anterior knee pain is unknown. We conducted a single-centre, outcome-assessor and patient-blinded, parallel-group, randomised, controlled trial to compare circumpatellar electrocautery with no electrocautery in total knee replacement in the absence of patellar resurfacing. Patients requiring knee replacement for primary osteoarthritis were randomly assigned circumpatellar electrocautery (intervention group) or no electrocautery (control group). The primary outcome measure was the incidence of anterior knee pain. A secondary measure was the standardised clinical and patient-reported outcomes determined by the American Knee Society scores and the Western Ontario and McMaster Universities (WOMAC) osteoarthritis index. A total of 131 knees received circumpatellar electrocautery and 131 had no electrocautery.

The overall incidence of anterior knee pain at follow-up at one year was 26% (20% to 31%), with 19% (12% to 26%) in the intervention group and 32% (24% to 40%) in the control group (p = 0.02). The relative risk reduction from electrocautery was 40% (9% to 61%) and the number needed to treat was 7.7 (4.3 to 41.4). The intervention group had a better mean total WOMAC score at follow-up at one year compared with the control group (16.3 (0 to 77.7) versus 21.6 (0 to 76.7), p = 0.04). The mean post-operative American Knee Society knee scores and function scores were similar in the intervention and control groups (knee score: 92.4 (55 to 100) versus 90.4 (51 to 100), respectively (p = 0.14); function score: 86.5 (15 to 100) versus 84.5 (30 to 100), respectively (p = 0.49)).

Our study suggests that in the absence of patellar resurfacing electrocautery around the margin of the patella improves the outcome of total knee replacement.

The August 2015 Children’s orthopaedics Roundup³⁶⁰ looks at: Learning the Pavlik; MRI and patellar instability; Cerebral palsy and hip dysplasia; ‘Pick your poison’: elastic nailing under the spotlight; Club feet and surgery; Donor site morbidity in vascularised fibular grafting; Cartilage biochemistry with hip dysplasia; SUFE and hip decompression: a good option?

The management of patients with a painful total knee replacement requires careful assessment and a stepwise approach in order to diagnose the underlying pathology accurately. The management should include a multidisciplinary approach to the patient’s pain as well as addressing the underlying aetiology. Pain should be treated with appropriate analgesia, according to the analgesic ladder of the World Health Organisation. Special measures should be taken to identify and to treat any neuropathic pain. There are a number of intrinsic and extrinsic causes of a painful knee replacement which should be identified and treated early. Patients with unexplained pain and without any recognised pathology should be treated conservatively since they may improve over a period of time and rarely do so after a revision operation.

Normal function of the patellofemoral joint is maintained by a complex interaction between soft tissues and articular surfaces. No quantitative data have been found on the relative contributions of these structures to patellar stability. Eight knees were studied using a materials testing machine to displace the patella 10 mm laterally and medially and measure the force required. Patellar stability was tested from 0° to 90° knee flexion with the quadriceps tensed to 175 N. Four conditions were examined: intact, vastus medialis obliquus relaxed, flat lateral condyle, and ruptured medial retinaculae. Abnormal trochlear geometry reduced the lateral stability by 70% at 30° flexion, while relaxation of vastus medialis obliquus caused a 30% reduction. Ruptured medial retinaculae had the largest effect at 0° flexion with 49% reduction. There was no effect on medial stability. There is a complex interaction between these structures, with their contributions to loss of lateral patellar stability varying with knee flexion.

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.

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.

We have reviewed the literature to establish the role of lateral retinacular release in the management of disorders of the extensor apparatus of the knee. The scientific evidence for intervention is explored and reports on outcome are discussed.

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.

Medial patellofemoral ligament (MPFL) reconstruction is used to treat patellar instability and recurrent patellar dislocation. Anatomical studies have found the MPFL to be a double-bundle structure. We carried out a meta-analysis of studies reporting outcomes of patellofemoral reconstruction using hamstring tendon autograft in a double-bundle configuration and patellar fixation via mediolateral patellar tunnels.

A literature search was undertaken with no language restriction in various databases from their year of inception to July 2012. The primary outcome examined was the post-operative Kujala score. We identified 320 MPFL reconstructions in nine relevant articles. The combined mean post-operative Kujala score was 92.02 (standard error (se) 1.4, p = 0.001) using a fixed effects model and 89.45 (se 37.9, p = 0.02) using random effect modelling. The reported rate of complications with MPFL reconstruction was 12.5% (40 of 320) with stiffness of the knee being the most common. High-quality evidence in assessing double-bundle MPFL reconstruction is lacking. The current literature consists of a mixture of prospective and retrospective case series. High-quality randomised trials evaluating this procedure are still awaited.

Cite this article: Bone Joint J 2013;95-B:900–5.

We retrospectively analysed the MR scans of 25 patients with patellofemoral dysplasia and ten control subjects, to assess whether there was any change in the morphology of the patella along its vertical length. Ratios were calculated comparing the size of the cartilaginous and subchondral osseous surfaces of the lateral and medial facets. We also classified the morphology using the scoring systems of Baumgartl and Wiberg. There were 18 females and seven males with a mean age of 20.2 years (10 to 29) with dysplasia and two females and eight males with a mean age of 20.4 years (10 to 29) in the control group.

In the patient group there was a significant difference in morphology from proximal to distal for the cartilaginous (Analysis of variance (ANOVA) p = 0.004) and subchondral osseous surfaces (ANOVA, p = 0.002). In the control group there was no significant difference for either the cartilaginous (ANOVA, p = 0.391) or the subchondral osseous surface (ANOVA, p = 0.526).

Our study has shown that in the dysplastic patellofemoral articulation the medial facet of the patella becomes smaller in relation to the lateral facet from proximal to distal. MRI is needed to define clearly the cartilaginous and osseous morphology of the patella before surgery is considered for patients with patellofemoral dysplasia.