Up to 10 year follow-up of the Oxford Domed Lateral Partial Knee Replacement from an independent centre.

BACKGROUND: The Oxford Domed Lateral Partial Knee Replacement (ODLPKR) was designed specifically for the lateral compartment in response to the unacceptable dislocation rate seen with the Oxford Partial Knee. This paper presents the up to 10-year follow-up of an independent, single surgeon series using this implant. The aim of this study is to assess the medium term outcome of the ODLPKR. The primary outcome measures were 13 revision surgery, re-operation and functional outcome. METHODS: Sixty-four knees in 58 patients were performed between 2005 and 2009. Patients were interviewed by telephone to determine whether further surgery had been conducted on their knee and to complete an Oxford Knee Score (OKS) questionnaire. RESULTS: The status of 61 knees was confirmed with a median follow-up period of 84months. One patient sustained two bearing dislocations ultimately requiring an elective bearing exchange. Two knees underwent revision to TKR and five other patients reported further operations. Median OKS was 26 (range nine to 36) pre-operatively and 42 (10-48) at final follow-up. CONCLUSION: The ODLPKR offers an effective and safe treatment for lateral compartment osteoarthritis. Bearing dislocation does not appear to be a significant issue with this implant and implant retention is similar to that achieved by medial unicompartmental knee replacements in the medium term.

Early results of a domed tibia, mobile bearing lateral unicompartmental knee arthroplasty from an independent centre.

AIM: The aim of this study is to determine the short-term outcome of lateral unicompartmental knee arthroplasty (UKA) using a domed tibia, mobile bearing prosthesis. The primary outcome measure was revision due to bearing dislocation and the secondary measure was functional outcome. METHODS: From 2005 to 2009, a total of 64 knees, in 58 patients, were identified as having the domed tibia, mobile bearing lateral UKA with a minimum 2-year follow-up. Forty-one females and 17 males with a mean age of 71years (range 44 to 92, median 72) were reviewed. The mean follow-up period was 38months (range 24 to 61, median 36). The primary outcome measure was re-operation and revision rate, particularly due to bearing dislocation. The secondary outcome assessed was a patient reported outcome measure (PROM) using the Oxford Knee Score (OKS) and compared using Student's Paired T-test. RESULTS: There were four knees that underwent further surgery for any reason. Two patients required revision of the implant (3.1%). There were no cases of bearing dislocation in this series. The mean pre-operative OKS was 24 (range 9 to 36) and the mean post-operative score was 42 (range 23 to 48 p<0.0001). CONCLUSION: This study from an independent centre, reporting on the short-term results of the domed tibia, mobile bearing lateral UKA supports the safety and efficacy of the procedure as a treatment option in the patients with lateral compartment osteoarthritis (OA) of the knee. LEVEL OF EVIDENCE: This is a level 4; case series study.

The effects of intramuscular tenotomy on the lengthening characteristics of tibialis posterior: high versus low intramuscular tenotomy.

BACKGROUND: Lengthening of soft-tissue contractures is frequently required in children with a wide variety of congenital and acquired deformities. However, little is known about the biomechanics of surgical procedures which are commonly used in contracture surgery, or if variations in technique may have a bearing on surgical outcomes. We investigated the hypothesis that the site of intramuscular tenotomy (IMT) within the muscle-tendon-unit (MTU) of the tibialis posterior (TP) would affect the lengthening characteristics. METHODS: We performed a randomized trial on paired cadaver tibialis posterior muscle-tendon-units (TP-MTUs). By random allocation, one of each pair of formalin-preserved TP-MTUs received a high IMT, and the other a low IMT. These were individually tensile-tested with an Instron(®) machine under controlled conditions. A graph of load (Newtons) versus displacement (millimetres) was generated for each pair of tests. The differences in lengthening and load at failure for each pair of TP-MTUs were noted and compared using paired t tests. RESULTS: We found 48% greater lengthening for low IMT compared to high IMT for a given load (P = 0.004, two tailed t test). Load at failure was also significantly lower for the low IMT. These findings confirm our hypothesis that the site of the tenotomy affects the amount of lengthening achieved. This may contribute to the reported variability in clinical outcome. CONCLUSIONS: Understanding the relationship between tenotomy site and lengthening may allow surgeons to vary the site of the tenotomy in order to achieve pre-determined surgical goals. It may be possible to control the surgical "dose" by altering the position of the intramuscular tenotomy within the muscle-tendon-unit.

Posterior divergent dislocation of the elbow in children and adolescents: a report of three cases and review of the literature.

Divergent dislocation of the elbow is defined as a specific elbow dislocation in which the distal humerus is forced between the proximal radius and ulna, resulting in separation or divergence of the proximal forearm bones. This is an uncommon injury in children, with 14 cases reported in the last 23 years. The authors report three additional cases and the findings from cadaver elbow dissections in which the injury was reproduced. The authors propose that there is only one type of divergent dislocation, resulting from indirect forces transmitted to the elbow from a fall on the outstretched hand. The injury predominantly occurs in younger children because joint laxity is a predisposing cause. Early recognition, followed by a closed reduction and a 3- to 4-week period of cast immobilization, should result in a full recovery for most children.

Accuracy of computed tomography guided core needle biopsy of musculoskeletal tumours.

BACKGROUND: The accurate diagnosis of musculoskeletal tumours is important for successful treatment. Image guided biopsy is gaining increasing acceptance for obtaining tissue for diagnosis. The aim of the present study is to assess the accuracy of computed tomography (CT)-guided core needle biopsy of musculoskeletal tumours. METHODS: This is a retrospective study on a series of 127 patients with a musculoskeletal tumour. The biopsies were performed over a 4-year period from 1998 to 2001. The accuracy of the CT-guided core needle biopsy was determined by comparing the histology of the biopsy with the final histology of the specimen obtained at open biopsy or surgical resection of the tumour. The effective accuracy was determined by the accuracy of the biopsy to distinguish between a benign and malignant tumour. RESULTS: Computed tomography guided core needle biopsy in the present series has an overall accuracy of 80.3%. The effective accuracy as determined by a malignant versus benign lesion was 89%. There were 86 malignant tumours with a biopsy accuracy of 81.4% and there were 41 benign tumours with a biopsy accuracy of 78%. The positive predictive value (PPV) of a malignant tumour is 98.9% and the PPV of benign tumour 90.2%. The most common site of biopsy was from the femur and thigh, together accounting for 39.4% of the tumours. The most common tumours in this series were liposarcoma (n = 12), osteosarcoma (n = 11) and giant cell tumour (n = 11). There were no reported complications arising from the biopsy. CONCLUSION: Computed tomography guided core needle biopsy is a safe and effective procedure that is important in the diagnosis and management of musculoskeletal tumours. It should be performed in a specialized institution with a multidisciplinary musculoskeletal tumour team.