Aims

The aim of this consensus was to develop a definition of post-operative fibrosis of the knee.

The objective was to compare vastus lateralis muscle splitting verses muscle sparing surgical approach to proximal femur for fixation of intertrochanteric fracture.

Of the 16 patients in this prospective randomised double blind study 8 were randomised to vastus lateralis muscle splitting and rest to muscle sparing group. Main outcome measurement was assessment of status of vastus lateralis muscle at 2 and 6 weeks using nerve conduction study. Preoperative demographics were identical for both the groups.

There was no statistically significant difference between the groups with regards to velocity, latency, and amplitude. The postoperative haemoglobin drop, heamatocrit, position of the dynamic hip screw and mobility status were identical.

Both clinical and neurophysiological outcome suggest that damage done to vastus lateralis either by splitting or elevating appears to be identical.

Introduction: Current Literature is sparse with respect to the optimum surgical approach for fixation of a fractured neck of Femur. A cadaveric study has been performed to determine the pattern of innervation of the Vastus Lateralis muscle. Results indicate that a muscle splitting technique may cause more nerve damage than a muscle reflection technique. The purpose of this study was to determine the clinical and neurophysiological effects of two different surgical approaches to the proximal femur.

Methods: Patients were randomised to receive either a Vastus splitting approach or a Vastus reflecting approach to the fractured femoral neck. The contralateral leg was used as the control for neurophysiological investigation. Needle electromyography was performed on both the operated and unoperated limbs within 2 weeks of surgery.

Results: 25 patients were included in the study randomisation. A total of 17 patients completed neurophysiological investigation, 8 in muscle reflection and 9 in muscle splitting groups. There was a significant reduction in femoral nerve conduction velocity compared to the unoperated control side in the muscle split group. This was also the case for amplitude of response measured in the Vastus muscle. The muscle reflection group showed no significant differences in these parameters compared to the unoperated side.

Conclusion: On the basis of the results of this study we recommend a Vastus Lateralis reflecting approach for proximal Femoral fracture fixation. The functional outcome of a muscle splitting approach remains unclear but could be investigated as part of a larger trial.

Introduction: There is an increased risk of revision for aseptic loosening with a transgluteal approach as described in the Swedish Hip Register. Femoral component malpositioning is itself associated with a poor outcome. A cuff of posteriorly situated glutei during the direct lateral approach may result in levering the proximal stem anteriorly and the tip of the stem posteriorly and does not allow the entry point of the stem to be placed posteriorly at the level of neck resection resulting in possible malpositioning.

The purpose of this study was to determine whether there is a significant difference in femoral component alignment when the posterior and direct lateral approaches are compared.

Materials and methods: Forty patients underwent an direct lateral approach and forty a posterior approach (n = 80). Inclusion criteria included primary hip arthroplasty using a cemented Exeter femoral component. At 6 weeks a standard AP and a modified lateral radiograph were taken. Measurements were taken from digitized radiographs as follows:

1. AP radiograph

Component alignment was defined as A – B and C – D.

Results: A–B was 0.71 for the modified direct lateral approach and 2.56 for the posterior approach. C–D was 1.47 for the direct lateral approach and 1.21 for the posterior approach. This difference was not statistically different using paired t tests as p > 0.05(P=0.69) for lateral views measurements.

Discussion: This study demonstrates that there is no significant difference between direct lateral and posterior approaches as far as femoral component alignment is concerned. The increased revision rate noted by the Swedish Hip Register when a transgluteal approach is likely to be multifactorial, but not likely to be due to femoral component malalignment.

Introduction: There is an increased risk of revision for aseptic loosening with a transgluteal approach as described in the Swedish Hip Register. Femoral component malpositioning is itself associated with a poor outcome. A cuff of posteriorly situated glutei during the direct lateral approach may result in levering the proximal stem anteriorly and the tip of the stem posteriorly and does not allow the entry point of the stem to be placed posteriorly at the level of neck resection resulting in possible malpositioning.

The purpose of this study was to determine whether there is a significant difference in femoral component alignment when the posterior and direct lateral approaches are compared.

Materials and methods: Forty patients underwent a direct lateral approach and forty a posterior approach (n = 80). Inclusion criteria included primary hip arthroplasty using a cemented Exeter femoral component. At 6 weeks a standard AP and a modified lateral radiograph were taken. Measurements were taken from digitized radiographs as follows:

AP radiograph

Tip of stem to outer medial cortex.

Component alignment was defined as A – B and C – D.

Results: A–B was 0.71 for the modified direct lateral approach and 2.56 for the posterior approach. C–D was 1.47 for the direct lateral approach and 1.21 for the posterior approach. This difference was not statistically different using paired t tests as p > 0.05(P=0.69) for lateral views measurements.

Discussion: This study demonstrates that there is no significant difference between direct lateral and posterior approaches as far as femoral component alignment is concerned. The increased revision rate noted by the Swedish Hip Register when a transgluteal approach is likely to be multifactorial, but not likely to be due to femoral component malalignment.

The effect of screw geometry on the pullout strength of Anterior Cruciate Ligament [ACL] reconstruction is well documented. Most research has looked at the effect of screw length and diameter, however other factors such as the degree of taper may also be important. Tapered screws should in theory be associated with increased pullout strength. This has not been demonstrated either clinically or in vitro before. The aim of this study was to compare the pullout strength of ACL reconstruction with a parallel against a tapered screw.

A parallel and tapered screw were manufactured which were identical in all other respects. Sixty superficial digital flexors from the hind legs of sheep were harvested. The tendons were paired and combined to form a quadruple tendon reconstruction of approximately 7mm diameter as measured with graft sizer. An ACL reconstruction was performed on the proximal tibia of 30 bovine knees, which had been harvested in right and left knee pairs, using the quadruple tendon. Fifteen reconstructions were fixed using tapered screws and fifteen with non-tapered screws. The insertion torque of both tapered and non tapered screws were recorded using an instrumented torque screwdriver. The reconstructions were mounted in an Instron materials testing machine with an x-ray bearing system to eliminate horizontal forces, to ensure that the forces were all directed along the line of the tibial tunnel. The maximum pullout strengths were recorded in each case. Five knee pairs were subjected to bone densitometry scanning to ensure that any difference in pull out strength was not due to changes in bone density between right and left knee pairs.

Results indicated that there was no difference between right and left knee pairs [p = 0.58] and that tapered screws were associated with significantly higher pull-out strengths [p=0.007] and insertion torques [p = 0.001].

Routine metalwork removal, in asymptomatic patients, remains a controversial issue in our daily practice. Current literature emphasized the potential hazards of implant removal and the financial implications encountered from these procedures. However, there is little literature guidance and no published research on current practice.

To estimate the current state of practice of orthopaedic surgeons in the United Kingdom regarding implant removal for limb trauma in asymptomatic patients, an analysis of the postal questionnaire replies of 36% (500 out of 1390) of randomly selected UK orthopaedic consultants was performed by two independent observers.

47.4% replies were received. A total of 205 (41%) were found to be suitable for analysis. The most significant results of our study I: 92% of orthopaedic surgeons stated that they do not routinely remove metalwork in asymptomatic skeletally mature patients. II: 60% of trauma surgeons stated that they do routinely remove metalwork in patients aged 16 years and under, while only 12% of trauma surgeons do routinely remove metalwork in the age group between 16–35 years. III: 87% of the practising surgeons indicated that they believe it is reasonable to leave metalwork in for 10 years or more. IV: Only 7% of practising trauma surgeons replied to this questionnaire have departmental or unit policy.

No policy is needed for metalwork removal, as most of the orthopaedic surgeons were complying with literature guidance supporting the potential risks associated with implant removal, in spite of the limited number of departmental or units’ policies on implant removal and the paucity of the literature documenting the current practice. However, there is a discrepancy among trauma surgeons in relation to metalwork removal between patient age groups. This indicates guidelines would be helpful to guide the surgeon for the best practice. This is important from a medico-legal standpoint because surgeons are being criticised for not achieving satisfactory results in negligence cases.

We hypothesise that the stiffness of the acetabular component influences the stresses transmitted to bone. Thus stress shielding or stress overload of the underlying host bone may be influenced by the choice of fixation method. In addition, we believe that the so called “brake drum effect” plays a significant role in the development of rim stresses and subsequent failure of fixation.

We have constructed a jig which allows the direct comparison, under controlled conditions, of contact stresses measured behind the acetabular component of polyethylene controls, uncemented metal backe cups and cemented all polyethylene cups, under physiological load. The design of the jig also allows measurement of stresses transmitted to the acetabular rim of the same three prostheses in order to confirm the presence and magnitude of the brake drum effect. The contact stresses are measured by miniature pressure transducers which are inserted through specially drilled holes in the shell of the jig so that the transducer is flush with the prosthesis under test. A total of 6 transducers are arranged in concentric circles radiating away from the prosthetic dome, so that contact stresses may be directly measured in various parts of the acetabular bed under conditions that reproduce as closely as possible the situation in a total hip prosthesis in vivo. Thus our method can be compared to other laboratory and theorectical techniques for investigation into stress transmission around acetabular components. The transducers were callibrated prior to each test to ensure parity of test results. The transducers were prestressed to ensure contact prior to each test. 6 polyethylene uncemented liners were tested alone in the jig to act as a control. In the same fashion, the same 6 polyethylene components were tested firstly in an uncemented, metal back acetabular component, and then as a cemented, all polyethylene component.

The results indicate that significantly less stress is transmitted to bone when metal back components are used as compared to cemented components and controls. The data confirms that the brake drum effect occurs in both cemented and uncemented prostheses, leading to at least the absence of compressive forces at the prosthetic rim and in some circumstances tensile forces.

We compared magnetic resonance imaging (MRI) scans and plain antero-posterior (AP) and lateral radiographs of 100 randomly selected patients in order to detect segmental abnormalities of the lumbar spine. We started by identifying those who appeared to have a segmental defect of the lumbar spine on MRI scan. We then checked all 100 plain radiographs to detect the true rate of segmental abnormality. We detected 17 patients with a segmental abnormality that correlates well with other studies. We believe that MRI scanning alone is not sufficient to detect reliably all segmentation defects in the lumbar spine, and that a plain lateral and an AP x-ray is also required. Of those who do have a segmentation disorder we have identified a sub-group who are at risk of surgery at the wrong level, if the correct pre-operative work-up is not performed. The difficulty will occur when a segmental abnormality is present (as determined by plain radiographs) and it is missed by MRI scan, and plain films are not taken, and the correct level is determined by counting upwards from the lumbosacral take-off angle using the image intensifier in theatre. We believe that all patients undergoing nerve root decompression should have an AP and lateral plain film and an MRI scan as well as pre-operative image intensification in theatre. Although the number of patients that would be affected by this is small, the consequences of operating on the wrong level are well recognised and can be avoided by being aware of the potential problem and by adhering to the above recommendations.

Introduction: We hypothesise that the fixation method of the acetabular component influences stress transmission to the host bone in vivo. We believe that the frequency of appearance of radiolucent lines at the prosthetic rim is directly related to the brake drum effect whereby compressive forces at the dome of a semi-rigid body leads to tensile forces at the rim.

Method: A series of miniature pressure transducers were manufactured and positioned at the prosthetic/ bone interface of an acetabular component of a total hip arthroplasty (THA) in a jig designed to replicated the loading conditions of a THA in vivo. The transducers were arranged in a series of five concentric rings spaced from the centre of the acetabular dome to the prosthetic rim. A total of six transducers was used. Three separate experiments were performed: 1. a polyethylene component alone to act as a control. 2. a polyethylene component surrounded by a cement mantle and 3. a polyethylene component surrounded by a metal-back. A separate jig was constructed to provide a cement mantle of the same thickness as the metal back. The stress transmitted to the host bone was measured in each case.

Results: The results indicated that successively less stress was transmitted when changing from controls to cemented then to metal-backed cups. Both cemented and uncemented cups demonstrated at the very least absence of compressive forces at the prosthetic rim and in some cases tensile forces, indicating that the brake drum effect is likely.

Introduction: Reports of the results of screw-cup arthroplasties have been disappointing with high revision rates.

Aim: To review our experience of 173 HA-coated screw- cups that have been implanted in 150 patients.

Methods: The patients were followed up at six weeks, three months, six months, again at one year and annually thereafter. The patients were assessed using the Merle D’ Aubigne (MDP) clinical scoring scale and by radiographic review.

Results: The average follow-up was 6.5 years (range 5–9 years). The follow-up rate was 93%. Two patients had revision surgery for recurrent dislocations (1.2%). Two patients were revised for aseptic loosening (1.2%). One patient underwent revision surgery for to deep prosthetic infection (0.6%) and two patients were revised for polyethylene wear without loosening (1.2%). This gave a total revision rate of 4.0%. The average post operative MDP scores were 5.7 for pain, 5.5 for range of movement and 5.4 for function. A radiological review revealed one patient with extensive granuloma formation and two patients with evidence of migration although no cups were revised for migration alone.

Discussion: We believe that the lower revision rate in this series is due to the double advantage of an HA coated cup (which leads to low revision rates for aseptic loosening), and the use of a ceramic head (which produces low polyethylene wear rates). We believe our results convey strong evidence for the advantage offered by HA coating for use with a screw-cup or other prosthesis.