Aims

Prosthetic joint infection (PJI) and aseptic loosening in total hip arthroplasty (THA) can present with pain and osteolysis. The Musculoskeletal Infection Society (MSIS) has provided criteria for the diagnosis of PJI. The aim of our study was to analyze the utility of F18-fluorodeoxyglucose (FDG) positron emission tomography (PET) CT scan in the preoperative diagnosis of septic loosening in THA, based on the current MSIS definition of prosthetic joint infection.

Introduction

Fluorodeoxuglucose(FDG) Positron Emission Tomography(PET) scan is used in the diagnosis of prosthetic joint infection, when the inflammatory markers and aspiration of the joint do not establish a definitive diagnosis. The aim of our study was to analyse the utility of FDG PET scan in decision making in these patients.

High failure rates have been associated with large diameter metal-on-metal total hip replacements (MoM THR). However there is limited literature describing the outcomes following the revision of MoM THR for adverse local tissue reaction (ALTR).

A total of 98 large diameter MoM THRs underwent revision for ALTR at our institution. The data was obtained from the clinical records and included the demographics, intra-operative findings of ALTR and post-operative complications. Any subsequent procedures and re-revision for any reason was analysed in detail. The clinical outcome was measured using functional outcome scores using the Oxford hip score (OHS), Western Ontario and McMaster Universities osteo-arthritis index (WOMAC) score and Short Form (SF12).

The mean age of the patients at the time of revision was 58.2 yrs. At a mean follow-up of 3.9 years (1.0 to 8.6) from revision for ALTR, there were 15 hips (15.3 %) with post-operative complications and 8 hips (8 %) requiring re-revision. The Kaplan–Meier five-year survival rate for ALTR revision was 91 % (95% confidence interval 78.9 to 98.0). There were no statistically significant predictors of re-revision. The rate of postoperative dislocation following revision was 9.2% (9 hips). The post-operative functional outcome depends on the intra-operative findings of tissue destruction secondary to ALTR.

The short term results following revision of large diameter MoM THR for ALTR are comparable with other reports in the literature. The use of constrained liners reduces the incidence of post-operative dislocation. There is an increased risk of postoperative instability following revision THR for ALTR. Early identification and intervention seems to be the logical approach in the management of patients with ALTR.

Introduction

This study was to investigate the association of developmental dysplasia of the hip (DDH) and primary protrusion acetabuli (PPA) with Vitamin D receptor polymorphisms TaqI and FokI and oestrogen receptor polymorphisms Pvu II and XbaI.

Purpose of study: To study the effect of an additional locking screw on fracture strain and stability in tibias undergoing intramedullary nailing.

Methods: An additional locking hole was drilled into four tibial nails, 185 mm from the proximal end of the 8 mm x 315 mm solid tibial nails. The nails were locked proximally and distally into a triple strain-gauged sawbone. An osteotomy was created distal to the additional hole, and the construct loaded axially, in flexion and extension, and in torsion with and without the extra locking screw. With the additional locking screw in place, strain increased at the proximal strain gauge site during loading in neutral by 17% (139 mϵ, 91–198) (p=0.01) and flexion by 8% (65 mϵ, 60–73) (p< 0.005). Strain decreased on loading in extension by 10% (141 mϵ, 62–243) (p=0.0497). The extra locking screw decreased strain at the gauge closest to the osteotomy site in all loading positions. Strain showed an overall increase with axial loading of 14% (47 mϵ, 4–105) (p=0.16), an increase with loading in flexion of 2% (9 mϵ, −38 to 62) (p=0.75) but a decrease of 47% (254 mϵ, 6–549) (p=0.18) with loading in extension. A significant reduction in angular motion at the osteotomy site occurred with the addition of the extra locking screw (21° at 34.5 Nm without the screw, 13° at 34.5 Nm with the screw, p=0.001). Additional hole in the shaft of the nail lead to increase the stress from 29 – 48 mPa (29 – 48 N/mm2) but did not fail when vertically loaded with 450 Newtons applied at rate of 5Hz sinusoidal waves for 2 million cycles.

Conclusion: Nails with additional locking options, by altering strain and motion at the fracture site, may have the clinical potential to affect fracture healing with relatively low risk of implant failure.

Objective- To evaluate three femoral cement pressurization techniques in a laboratory setting.

Design- Observational study using a plastic femur (sawbone) model.

Materials and Methods- 12 femoral bone models were cemented and pressurized using three different cement pressurization techniques (standard technique, pressuriser in situ technique, and thumb pressurisation technique). Four sets of observations were taken for each technique. Intramedullary pressure readings were obtained using proximal and distal pressure monitoring transducers. The peak pressure and the time for which the pressure was above a particular cut off level (5 KPa and 100 KPa) were compared.

Results- There were significant variations between the peak pressure and the duration for which the pressure was above 100 KPa. The pressuriser in situ technique yielded significantly (p< 0.001) higher peak pressure both proximally (397.5 ± 40.2 KPa) and distally (597.3 ± 102.4). The standard technique produced the optimum pressure of 100 KPa for significantly (p< 0.001) longer duration proximally and distally (66.8 ± 29.5 and 45.2 ± 15.5 seconds respectively) compared to the other two techniques (less than 5 and 17 seconds for thumb pressurisation technique and pressuriser in situ technique respectively, both proximally and distally). There were no significant statistical differences between the three methods for the time for which the cement pressure was higher than 5 KPa.

Conclusion- Although the pressuriser in situ technique produced highest peak pressure, the standard technique produced optimum pressure for longer duration. The standard technique seems to be adequate to achieve optimum pressurization during femoral cementing without increased risk of embolisation.

Introduction: Peri-acetabular rotational osteotomy is recognized as the non-arthroplastic treatment for Developmental Dysplasia of the Hip (DDH). This procedure has increased in popularity during the last decade. It aims to restore the acetabular cover over the femoral head and thus delay secondary osteoarthritic changes in the hip.

Materials and methods: We reviewed 16 patients who underwent peri-acetabular rotational surgery at our hospital. The indication for surgery was DDH in all cases. Reinert’s approach was used for surgical exposure. Two patients underwent a valgus femoral osteotomy at the same time. Mean age was 40 years (range 15–49). The mean follow-up was 46.5 months (range 4–108). The results of the surgery were assessed with radiological indices and a patient satisfaction survey. The radiological indices recorded were Wiberg’s angle, acetabular inclination angle, femoral head extrusion index and Tonnis osteoarthritis grading.

Results: The intervention failed to benefit two patients who subsequently required a total hip arthroplasty. Both patients had Tonnis grade 3 osteoarthritis. One patient developed a necrotic skin flap requiring skin grafting. The mean pre-operative Wiberg’s angle was 11 degrees (range −7 to 25) which was corrected to 35 degrees (range 17 to 58). Mean pre-operative acetabular index was 25 degrees (range 14 to 40) which was corrected to 11 degrees (range of 2 to 21). Mean pre-operative femoral head extrusion index was 37 degrees (range 18–50) which was reduced to 14 degrees (range 0–32). In all but the two patients in whom the surgery had failed, patients reported reduction in hip pain.

Conclusions: Peri-acetabular rotational osteotomy is a challenging but worthwhile procedure for young patients with DDH. The early results from the procedure are encouraging providing patient selection is appropriate. We would like to initiate a debate to identify the ideal patient for this procedure.