The optimal method of fixation for primary total hip replacements (THR), particularly fixation with or without the use of cement is still controversial.

In a systematic review and meta-analysis of all randomized controlled trials (RCT) comparing cemented versus uncemented THRS available in the published literature, we found that there is no significant difference between cemented and uncemented THRs in terms implant survival as measured by the revision rate.

Better short-term clinical outcome, particularly an improved pain score can be obtained with cemented fixation. However, the results are unclear for the long-term clinical and functional outcome between the two groups. No difference was evident in the mortality and the post operative complication rate. On the other hand, the Radiographic findings were variable and do not seem to correlate with clinical findings as differences in the surgical technique and prosthesis design might be associated with the incidence of osteolysis.

We concluded in our review that Cemented THR is similar if not superior to uncemented THR, and provides better short term clinical outcomes. Further research, improved methodology and longer follow up are necessary to better define specific subgroups of patients in whom the relative benefits of cemented and uncemented implant fixation can be clearly demonstrated.

Introduction

It is recommended that the ankle be held in dorsiflexion at the time of placement of syndesmosis screw. We assessed the validity of this recommendation.

Objective: The deltoid ligament is an important stabilising structure in the ankle joint. We hypothesised that ultrasound can be used to allow early clinical assessment of ankle fracture stability accurately and quickly in Weber B and C ankle fractures thereby negating the need to perform arthrograms intra-operatively.

Method: A total of 20 patients were recruited prospectively. Consent was obtained prior to surgery. Patients with Weber B or C fractures requiring surgery were recruited prospectively. Following induction of anaesthesia, ultrasound examination was performed, followed by an arthrogram under fluoroscopic screening. Operating surgeons were blinded to results. Radiographs, ultrasound and arthrographic findings were compared by a panel of orthopaedic surgeons of varying grades (2 Consultants, 2 Specialist Registrars).

Results: There was 95% correlation between ultrasound and arthrogram findings. Ultrasound accurately diagnosed rupture with a sensitivity of 92% and specificity of 100%. Kappa scores for ultrasound identification of deltoid rupture was 0.8.

Conclusion: We feel ultrasound exam to be a powerful adjunct tool in the management and operative planning of ankle fractures. Its versatility means it can be used in Emergency Departments and Trauma Clinics to assess ankle stability without causing the patient excessive pain and requiring an anaesthetic.

Introduction: Weber B fractures are one of the most common fractures of the ankle. Unstable fractures are treated with lateral plating and a lag screw. Another method of fixation is antiglide plating, this concept was first introduced by Brunner and Weber in 1982.

Manoli and Schaeffer in 1987, showed that fixation by antiglide plate demonstrated superior static biomechanical properties compared to lateral plating.

However there are some shortcomings in their study and hence we decided to perform our biomechanical study. The shortcomings of the Manoli study are. They did not use an interfragmentary lag screw for lateral plate fixation. It was a cadaveric study where the bone does not accurately represent the live bone. The quality of the bone ranging from normal to osteoporotic bone varies from cadaver to cadaver and hence there is no uniformity between the samples.

Materials and Methods: We used 4th generation composite bone models validated to closely simulate human bone characteristics for fracture toughness, tensile strength, compressive strength, fatigue crack resistance and implant subsidence. 4th generation composite bone model provides uniformity of test samples which is not achievable in cadaveric studies.

These bones were custom made for the experiment. We used two sets of bones, one representative of normal bone (Set A n=10) and the other of osteoporotic bone quality (Set B n=10). Each of the sets A & B will have two types of fixations for artificially created Weber B Fractures.

Lateral plate with interfragmentary lag screw.

The strength of the fixation was measured by restressing the bone until the fixation failed using an Instron machine which simultaneously applied torque and compressive forces to the fibular construct. The resulting data was analysed on a computer and statistical analysis was performed.

Results: When the two fixation constructs were stressed to failure, the lateral plate construct demonstrated less stiffness (3–5Nm/degree) and failed at lower energy levels (250Nm). Similar values obtained for the antiglide system were, stiffness of 12–16Nm/degree and energy absorbed to failure 350–450Nm. Antiglide plating was significantly more stable in the osteoporotic fibula.

Conclusion: Antiglide plating with lag screw is much more stable than lateral plating. It is suitable for treatment without plaster cast post operatively. It results in a more stable fixation in osteoporotic bone.

Introduction: Traditionally the fixation of choice as recommended by the AO ASIF group for transverse fractures of the Olecranon and the Patella is the tension band wiring technique.

The concept of tension band wiring is based on the fact that the distractive force applied to one surface of the bone will result in compression on the opposite articular surface.

Clinical outcomes of TBW are not equivocal. It is associated with significant morbidity such as non union, failure of fixation, especially in osteoporotic bone and infection which sometimes leads to amputation. Often a second procedure for removal of prominent metal work is required.

In our biomechanical study we investigated this concept as we believe that the forces generated by TBW construct do not generate significant compressive forces required for healing of fracture.

Materials and Methods: We used 4th generation composite bones (Sawbones^®, Malmoe, Sweden.). These bone analogues have been validated to closely simulate human bone characteristics for fracture toughness, tensile strength, compressive strength, fatigue crack resistance and implant subsidence.

The advantage of using 4th generation composite bone model is that it provides uniformity which is not achievable in cadaveric studies. Two different bone models representative of Olecranon and patella were used. Transverse fractures were created in the bones and fixed with TBW technique as described in A.O. manual.

Two 0.062-inch Kirschner wires and figure of eight configuration of 18G Stainless steel wire with single knot technique was used. Micro motion transducers (DVRT: MicroStrain, Williston, Vermont) with an accuracy of ± 1μm were placed across the fracture site both anteriorly and posteriorly. Continuous information regarding fracture distraction and compression, as determined by the transducers was recorded from both sites simultaneously during the experiment.

The tension band wire construct was loaded up to a maximum force of 4000 Newtons for patella and 500 for the olecranon. The fractures were subjected to cyclic loading at 1Hz using a servo hydraulic materials-testing system (model 8500; Instron, Canton, Massachusetts). The results were analysed on a computer and statistical analysis performed.

Results: During the application of cyclical loading, we noted a gap at the articular surface ranging from 1.1± 0.4mm and 2.1± 0.6mm for Olecranon and patella constructs respectively. During most of the duration of the experiment no transducer displacements were recorded at the articular surface.

Conclusion: The concept that distractive forces at one end could be converted to compression at the other end through the TBW does not hold true in our biomechanical study. A simpler construct may suffice for fixation of patellar and Olecranon fractures which can reduce the complications associated with TBW fixation.