Extracorporeal irradiation and re-implantation of a bone segment is a technique employed in bone sarcoma surgery for limb salvage in the setting of reasonable bone stock. There is neither consensus nor rationale given for the dosage of irradiation used in previous studies, with values of up to 300Gy applied. We investigated the influence of extracorporeal irradiation on the elastic and viscoelastic properties of bone. Bone specimens were extracted from mature cattle and subdivided into thirteen groups; twelve groups exposed to increasing levels of irradiation and a control group. The specimens, once irradiated, underwent mechanical testing in saline at 37°C.

Mechanical properties were calculated by experimental means which included Young's Modulus, Poisson's Ratio, Dissipation Factor, Storage Modulus, Loss Modulus and Dynamic Modulus. These were all obtained for comparison of the irradiated specimens to the control group.

We found there to be a statistically significant increase in Poisson's ratio after increasing irradiation doses up to 300Gy were applied. However, there was negligible change in all other mechanical properties of bone that were assessed. Therefore, we conclude that the overall mechanical effect of high levels of extracorporeal irradiation (300Gy) is minute, and can be administered to reduce the risk of malignancy recurrence.

This study assesses the incidence of noise in ceramic on ceramic (COC) bearings compared to metal on polyethylene (MOP) bearings. Noise after MOP implants has rarely been studied and they never been linked to squeaking.

We have developed a noise characterising hip questionnaire and sent it along with the Oxford Hip Score (OHS) to 1000 patients; 509 respondents, 282 COC and 227 MOP; median age 63.7 (range 45–92), median follow up 2.9 years (range 6–156 months).

47 (17%) of the COC patients reported noise compared to 19 (8%) of the MOP patients (P=0.048). 9 COC and 4 MOP patients reported their hip noise as squeaking. We found the incidence of squeaking in the COC hips to be 3.2% compared to 1.8% in the MOP hips. Overall, 27% patients with noise reported avoiding recreational activities because of it and patient's with noisy hips scored on average 4 points less in the OHS (COC: P=0.04 and MOP: P =0.007).

This is the first study to report squeaking from MOP hip replacements. We therefore believe the squeaking hip phenomenon is not exclusive to hard bearings. Surprisingly, only a small proportion of patients described nose from their as a ‘squeak’. Noisy hip implants may have social implications, and patients should be aware of this. We have shown a relationship between noise and a lower OHS. However, longer follow-up and further study is needed to link noise to a poorly functioning implant.

To validate the Modified Forgotten Joint Score (MFJS) as a new patient-reported outcome measure (PROM) in hip and knee arthroplasty (THR/TKR) against the UK's gold standard Oxford Hip and Knee Scores (OHS/OKS).

The MFJS is a new assessment tool devised to provide a greater discriminatory power, particularly in well performing patients. It measures an appealing concept; the ability of a patient to forget about their artificial joint in everyday life.

Postal questionnaires were sent out to 400 THR and TKR patients who were 1–2 years post-op. The data collected from the 212 returned questionnaires was analysed in relation to construct and content validity. 77 patients took part in a test-retest repeatability assessment.

The MFJS proved to have an increased discriminatory power in high-performing patients in comparison to the OHS and OKS, highlighted by its more normal frequency of distribution and reduced ceiling effects. 30.8% of patients (n=131) achieved excellent OHS/OKS scores of 42–48 this compared to just 7.69% of patients who achieved a proportionately equivalent MFJS score of 87.5–100. The MFJS proved to have an increased test-retest repeatability based upon its intra-class correlation coefficient of 0.97 compared to the Oxford's 0.85.

The MFJS provides a more sensitive tool in the assessment of well performing hip and knee arthroplasties in comparison to the OHS/OKS. The MFJS tests the concept of awareness of a prosthetic joint, rather than pain and function and therefore should be used as adjunct to the OKS/OHS.

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.