The longitudinal midline and medial-parapatellar incision are commonly used in Total Knee Arthroplasty (TKA). Medial-parapatellar incision n offers a smaller wound, avoids creation of thin skin flaps and easier exposure in obese patients. This incision creates a lateral skin flap which may be subject to poor blood supply and delayed wound healing.

We undertook a Randomised Controlled Trial (n=20) comparing midline and medial-parapatellar incisions. Cutaneous blood-flow was measured using a Doppler Imager. Interstitial fluid measurements for lactate, pyruvate, lactate/pyruvate ratio and glucose were obtained from subcutaneous microdialysis catheters. Wound cosmesis was graded and skin sensation tested.

Immediately post-op there was no significant difference in subcutaneous blood flow, but by day 3 patients with medial-parapatellar incisions showed greater bloodflow than midline incisions, particularly on the medial side (387 vs 278units p=0.148). At both day 1 and 3 post-op the lateral flap of the medial parapatellar incision showed decreased blood flow compared to the medial side, though these failed to reach significance. In contrast the midline incision showed no discernable difference in blood flow between the medial and lateral flaps. Concentrations of subcutaneous glucose increased from 4 hours post-op in the midline group, returning to baseline by 24hours. In contrast, the parapatellar group remained at base line throughout. Lactate concentrations increased over time in both groups peaking at 12hours post-op. No difference was noted between incision types with regard to wound cosmesis.

We conclude that the use of a medial-parapatellar incision results in only minimal biochemical changes, which are unlikely to alter wound healing. Medial-parapatellar incision is therefore a safe alternative to a midline incision and can be utilised in appropriate complex cases to aid surgical exposure.

Ponseti first advocated his treatment for idiopathic clubfoot in the early 1950's. The method has only gained popularity and widespread use since the 1990's. Despite publications showing favourable results, there is little published data scrutinising the change in modes of talipes treatment. This study sought to define the trends in treatment for Idiopathic Clubfoot in Scotland over a twelve-year period (1997 – 2008).

(i) A review was performed to identify the number of publications referencing the Ponseti method over the past 40 years. (ii) A structured questionnaire was sent to all Paediatric Orthopaedic practitioners in Scotland to ascertain the treatment methods used and over the time period. (iii) Data from the National Census for number of live births were combined with that obtained from the Scottish Morbidity Record (SMR01) for number of peritalar clubfoot surgeries performed over the study period. (iv) Similar data was also obtained for non-Talipes related peritalar surgeries, and data colleceted for the number of Tibialis Anterior transfer operations for this period. Clubfoot incidence data was measured indirectly by means of sample from the database of a tertiary referral Paediatric Orthopaedic Unit. Regression analysis was used to evaluate the trends over time.

Review of the literature referencing the Ponseti method over the past 40 years showed an exponential increase from the late 1990's. The survey of Clubfoot management of Paediatric Orthopaedic Surgeons in Scotland showed a marked increase in use of the method over with this period. Over this period, the number of operations for clubfoot dropped substantially, from 55 releases in 1997 to 1 release in 2008. The linear equation estimated a decrease of approximately 5 surgical releases per year (R²= 0.87, p<0.05). In Scotland, most Tibialis Anterior transfers are performed at age 3years, the frequency of the procedure has increased in the latter half of the study period.

In Scotland between 1997 and 2008, the number of peritalar (posterior, medial, posteromedial release) operations used in the primary treatment of idiopathic clubfoot has dropped substantially. This correlates with a marked increase in reference to the method within the literature and increased usage of the Ponseti technique by Paediatric Orthopaedic Consultants.

Ceramic-on-ceramic alumina bearings (ALX) have demonstrated low wear with minimal biological consequences for almost four decades. An alumina-zirconia composite (BIOLOX-DELTATM) was introduced in 2000 as an alternative ceramic. This contains well-distributed zirconia grains that can undergo some surface phase transformations from tetragonal to monoclinic. We analyzed 5 cases revised at 1–7 years to compare to our simulator wear studies. For the retrieved DELTA bearings, two important questions were

how much tetragonal to monoclinic transformation was there in the zirconia phase and

The retrieval cases were photographed and logged with respect to clinical and revision details. The DELTA balls varied from 22mm to 36mm diameters. These had been mated with liner inserts varying by UHMWPE, BIOLOX-FORTE and BIOLOX-DELTA materials. Bearing features were analyzed for roughness by white-light interferometry, for wear by SEM, for dimensions by CMM and for transfer layers by EDS technique. Surface transformations on DELTA retrievals were mapped by XRD. The four combinations of 36mm diameter BIOLOX-FORTE and BIOLOX-DELTA were studied in a hip simulator, which was run in ‘severe’ micro-separation test mode to 5 million cycles. Wear rates, wear stripes, bearing roughness and wear debris were compared to the retrieval data.

In two DELTA ball cases, there were conspicuous impingement signs, stripe wear and black metallic smears. It is to be noted that the metal transfer sites (EDS) appeared to be from the revision procedures. The retrieved balls run with alumina liners showed monoclinic phase peaking at 32% on the particular surface and internal bore. On the fracture surface of case 1, the monoclinic content had increased to 40%. Various surface roughness indices were assessed on the bearings. The polished articular surfaces averaged roughness (Sa) of the order 3 nm, representing extremely smooth surfaces. The main wear zone was only marginally rougher (5 nm). In contrast the stripe wear zones had roughness of the order 55–140 nm.

In the laboratory, the DELTA bearings provided a 3–6 fold wear reduction compared to FORTE controls. Roughness of stripes increased to maximum 113nm on controls. Roughness of wear stripes showed FORTE with the highest and DELTA with the lowest values. DELTA bearings also revealed much milder wear by SEM imaging. Phase transformations showed peaks at < 30% for both main wear zone and stripe wear sites. It is hypothesized that the concentration of monoclinic phase reached a certain level due to compression contraint imposed by the alumina matrix. With implant wear, additional tetragonal grains of zirconia are exposed and these will also transform to tetragonal. This consistency between laboratory and retrieval studies confirmed the stable nature of the bearings. The BIOLOX-DELTA combination provides optimal potential for a clinically relevant reduction in stripe wear.

Aims: To determine the anthropometric measurements of bony landmarks in the knee using MR scans and so assist revision knee surgeons in prostheses placement.

Methods: We analysed 100 MR scans of patients aged 16–50 (50 male, 50 female) which were performed for meniscal pathology, patellar dislocation and ACL injury. Those over the age of 50 or with symptoms suggestive of general osteoarthritis, or where the epiphyses had not yet fused were excluded. All measurements recorded were to the level of joint line and are shown below.

Results: (Tables removed)

Conclusions: To ensure near normal knee mechanics are achieved during revision knee surgery the joint line should be within 5mm of the original. Our study provides mean values for the distance from various bony landmarks to the joint line in non-arthritic knees on MR scan. The use of the medial epicondyle value as a sole reference will place the joint line within 5mm in 88% of males and 96% of females. Use of multiple landmarks further increases accuracy. The final position of the joint will depend on trialling prostheses.