Background

Hip Hemiarthroplasty is one of the commonest orthopaedic operation done in UK with recent NHFD data from 2017 report showing that 43% of the 77000 patients who presented to hospital had hemiarthroplasty. Literature suggests dislocation rate of 0.8% – 6.1% for Hip Hemiarthroplasty. Dislocation of hemiarthroplasty may lead to significant morbidity and mortality.

Creating cement keyholes (i.e. drilling simple holes in cancellous bone to allow cement filling) is a practice used in multiple scenarios in orthopaedic surgery to ensure improved fixation between the bone-cement interface and as such between bone and prosthesis. It is most commonly used in hip arthroplasty to secure fixation of the cup to the acetabulum by drilling keyholes in acetabulum. However very little research has been conducted into what the dimensions of such cement keyholes should be. The following laboratory based research was performed to provide insight into the optimum dimensions of cement keyholes.

The investigator designed a novel arrangement to enable testing of keyholes. Beechwood block models were then made to this design testing keyholes of varying diameters and depths. These were cemented with acrylic bone cement and then loaded to failure. A finite system analysis was also performed.

Results show that stresses are concentrated at the base of the keyhole. As such increasing diameter of keyhole infers greater strength, but there is no relationship between depth and strength. This has been further confirmed with finite element analysis. We suggest the width of cement keyholes bears more importance than the depth and propose drilling wide but shallow keyholes.

The Dawn Hip - An Effective Strategy to Improve the Management of Traumatic Hip Fractures

Neglected traumatic dislocation of hip in children is very rare and most of the studies are too small to draw a conclusion. There is no consensus on timing for closed VS open reductions and post reduction care. The aim of our prospective study was to analyse and characterise the short term treatment outcome of treating 20 such cases in children (<12 years). All had posterior dislocation without any associated fractures (Thompson & Epstein type 1) sustained during typical childhood play activities and/or a fall from a height less than 10 feet. All attended the hospital between 1-52 weeks of injury. Closed reductions under GA were performed in 12 cases which were less than 3 weeks old, followed by hip immobilisation for 3 weeks and PWB mobilisation for 3 weeks. 8 hips (> 3 weeks old) had open reductions as none of them could be reduced by skeletal tractions and were allowed for FWB mobilisation after 9 weeks. Functional result (Garrett et al) at 2 years follow-up showed a complete range of motion in 18 children while the remaining two had 80% of normal hip movements with no deformity. All the hips showed varying degrees of avascular necrosis, with preservation of joint space on radiographs (Ficat & Arlet stage 1-3). There were no redislocations.

We suggest that closed (for <3 weeks old dislocation) and open (for >3 weeks old dislocations) reductions are satisfactory treatment for traumatic neglected hip dislocations in children

We present an objective method for predicting the redisplacement of paediatric forearm and wrist fractures. Novel radiographic measurements were defined and their value assessed for clinical decision making. In Phase I of the study we defined the cast index and padding index and correlated these measurements with the incidence of fracture redisplacement. Phase II assessed these indices for their value in clinical decision making.

Cast Index (a/b) is the ratio of cast width in lateral view (a) and the width of the cast in AP view (b). Padding Index (x/y) isthe ratio of padding thickness in the plane of maximum deformity correction (x) and the greatest interosseous distance (y) in AP view. The sum of cast index and padding index was defined as the Canterbury Index.

In Phase I, 142 children's radiographs were analysed and a statistically significant difference was identified between redisplacement and initial complete off-ending of the bones, cast index > 0.8 and padding index of > 0.3. There was no significant association with age, fracture location, seniority of surgeon or angulation. In Phase II, radiographs of 5 randomly selected cases were presented to 40 surgeons (20 consultants & 20 registrars). Following an eyeball assessment they were asked to measure the cast index and padding index (after instruction). With eyeballing the consultants predicted 33% and registrars 25% of the cases that redisplaced. After learning to measure the indices the accuracy increased to 72% for consultants and 81% for registrars (p<0.001).

We conclude that the cast index, padding index and Canterbury Index are validated tools to assess plaster cast quality and can be used to predict redisplacement of paediatric forearm fractures after manipulation. They can easily be taught to orthopaedic surgeons and are more accurate than eyeballing radiographs in the clinical setting. Redisplacement can be predicted if cast index > 0.8, padding index > 0.3 and Canterbury Index > 1.1.

We assessed two simple radiological methods of predicting redisplacement of forearm fractures in children: a) Cast Index (ratio of sagittal to coronal cast width at the fracture site), and b) Padding Index (ratio of padding thickness at the fracture site in the plane of the deformity to the maximum interosseous width).

Case records and radiographs of 100 children who underwent a manipulation under general anaesthesia for a displaced fracture of forearm or wrist were studied. Redisplacement was defined as more than 15 degrees of angulation and/or more than 50 percent of translational displacement on check radiographs at 1–2 weeks.

Angulation (in degrees) and translation displacement (in percentage) were measured on the initial and check radiographs. Cast index and Padding index were measured on the check radiographs. Good intra and inter observer reproducibility was observed for both these measurements. The cast index was validated in an experimental study.

Redisplacement was seen in 29 cases. Of these 21 cases underwent a secondary procedure for redisplacement. Initial displacement, cast index and padding index were the three factors which were significantly higher in the redisplacement group (p< 0.05). The means and 95% Confidence intervals for cast index and padding index were 0.88 (0.84, 0.90) and 0.48 (0.39, 0.62) in the redisplacement group whereas were 0.71 (0.69, 0.72) and 0.11 (0.09, 0.12) in the group with no redis-placement respectively. No statistically significant difference was seen for age, fracture location, initial angular deformity and seniority of the surgeon.

Conclusion: cast index and padding index are simple and reliable radiographic measurements to predict the redisplacement of forearm fractures in children. A plaster with a cast index of> 0.9 and padding index of > 0.3 is prone to redisplacement.

Background: Resurfacing hip replacement is becoming increasingly used surgical option for young active patients with disabling hip arthritis.However there is a paucity of published literature describing complications and their avoidance.

Objective The objective of this study was to analyse 6 cases of postoperative subcapital fracture following hip resurfacing with a cohort of 54 cases that did not have a fracture and to identify factors associated with fractures risk.

Materials and Methods Between January 1999 and October 2003, 60 hips in 54 patients were treated with metal on metal resurfacing hip replacement (MMT Birmingham, UK).6 of these sustained a fracture just below the femoral component.The notes and radiographs were reviewed.Demographics data was recorded along with height, weight,smoking habits and medication usage including NSAIDS and antiepileptic use.The radiographs were studied for notching of the neck,offset difference as compared to normal and the stem shaft angle. The results were statistically analysed to determine any significant associations.

Results 57 hips in 51 patients were analysed for comparison. The mean age of the patients was 50 yrs (Range 34–67).In the fracture cases there were three men and three women with a mean age of 48 yrs.Five of six ( 83%) in the fracture cases had notching of the femoral necks compared to 9 (17%) out of 51 of the non fractured patients. The offset was significantly greater in the fractured group(52 ± 7mm) compared to the non fractured group (49 ± 7 mm).The increase in offset appeared to occur as a result of incomplete seating of tight fitting cemented femoral component. The head size appeared smaller in the fractured group but the difference was insignificant. There was no significant trauma in any of the cases. None of the patients who underwent resurfacing for AVN and cyst had a fracture. There were no other significant correlations

Conclusions Increased offset and notching are factors which predispose to fractures following resurfacing hip replacements. AVN and cysts were not associated with fractures in our series. We have changed the cementing technique using smaller volumes of freshly mixed simplex cement and now encourage protected weight bearing if intraoperative notching is noted or if osteoporosis is identified pre or peri operatively. We have had no fractures in the last 18 months.

Traumatic dislocation of the hip in children is rare. Large series have shown this injury to be 25 times less common in children than in adults. Only 70 cases of Neglected traumatic dislocation of hip in children has been reported in the English literatures and most of those studies are too small to draw a significant conclusions. We report our experience of treating 20 such cases of neglected traumatic dislocation of hip in children (< 12 years). All had posterior dislocations without any associated fracture. They attended the hospital between 1–52 weeks after injury.Closed reduction under G.A was performed in 12 cases which were less than 3 weeks old while 8 hips(> 3 weeks old) had open reductions following failed reductions with skeletal traction. At 2 years follow-up, a complete range of motion was found in 18 children while the remaining two had 80% of normal hip movement with no significant deformity. All the hips showed varying degree of avascular necrosis, with preservation of joint space on radiographs.

We suggest that attempted closed reduction of under 3 weeks old and open reductions for older dislocations gives satisfactory results. Also an anatomically placed femoral head maintains the stimulus for growth of pelvis and the femur.

The aims of this study were i) to see if there is an association between poorly applied plasters and redisplacement of paediatric forearm fractures, and ii) to define reliable radiographic measurements to predict redisplacement of these fractures. The two radiographic measurements which were assessed were Cast Index and Padding Index which are a guide to plaster moulding and padding respectively. The sum of these was termed as the Canterbury Index.

Case records and radiographs of 142 children who underwent a manipulation for a displaced fracture of forearm were studied. Angulation, translation displacement, Cast index and Padding index were measured on radiographs.

Redisplacement was seen in 44 cases (32.3%). The means and 95 % Confidence intervals for cast index and padding index were 0.87 (0.84, 0.90) and 0.42 (0.39, 0.62) in the redisplacement group whereas were 0.71 (0.69, 0.72) and 0.11 (0.09, 0.12) in the group with no redisplacement respectively. Initial displacement, Cast index, Padding index and Canterbury Index were significantly greater in the redisplacement group (p< 0.005). No statistically significant difference was seen for age, fracture location, initial angular deformity and seniority of the surgeon. We suggest that Cast Index > 0.8, Padding Index > 0.3 and Canterbury Index > 1.1 are significant risk factors for redisplacement of conservatively treated paediatric forearm fractures.

Approximately 46,000 total hip replacements are performed in the U.K. annually with a dislocation rate between 2 and 5%. Birmingham hip resurfacing (BHR) is a bone conserving metal on metal prosthesis, designed for young patients with hip arthroses that claims to substantially reduce the problem of dislocation. Derek McMinn has reported a personal series of 1,030 BHR’s with a dislocation rate of 0.001% (1 out of 1,030). We present a consecutive series of 55 BHR’s performed by one consultant between January 1998 and June 2001 with a dislocation rate of 7.3% (4 out of 55). 3 out of 4 dislocations occurred in anatomically abnormal hips (two occurred in a patient with developmental dysplasia of the hips and one with avascular necrosis of the femoral head). In this paper, we discuss the possible causes of dislocation in BHR. We suggest careful patient selection by less experienced surgeons to reduce the risk of dislocation following BHR.