Current opinion is divided as to whether carpal tunnel syndrome requiring operative decompression can be caused by an occupation. The aims of this study were to define the lamb freezing worker population who acquire carpal tunnel syndrome and to confirm or refute lamb boning as an occupational cause for carpal tunnel syndrome. Roles, gender age and exposure periods of all workers who had carpal tunnel decompressions over the past six seasons at the largest lamb Freezing Works in the world were examined. Kaplan-Meier survival analysis for boners, slaughter men and non-knife labourers was performed and tested for significance. Chi-square analysis and ANOVA were performed for gender and age. Age and gender-adjusted Cox regression analysis was performed to establish relative risks/hazard ratios for each of the three groups developing carpal tunnel syndrome. Incidences for boners and non-knife hands were calculated. Comparison of this population and a standard carpal tunnel population was performed. Two hundred and eighty five carpal tunnel decompressions were performed in workers who failed conservative management at the largest lamb freezing works in the world by a single surgeon after neurophyiological-test confirmation of the diagnosis. Of those having surgery 79% were men: 21% female and this was significant with Chi square testing (p<
0.01). At decompression boners were significantly younger than non-knife hands (p<
0.01). Adjusting for age and gender boners were 120% more likely to need decompression than non-knife labourers (p<
0.01). The median survival for a lamb boner’s carpal tunnel at five years was 44%. The incidence of carpal tunnel syndrome in lamb boners was 10% (person-seasons). This population is entirely different to the published idiopathic population requiring carpal tunnel decompression which is predominantly female with meanage of 55. To our knowledge this is the first study to provide sound evidence that carpal tunnel syndrome can be caused by an occupation. We have quantified this and welcome ideas for further work in this fascinating a uniquely New Zealand population.
The Morscher press fit acetabular component is a monobloc cup with the polyethylene bonded directly to a titanium mesh shell. There is little published data on the longevity of the Morscher cup apart from the designer’s series. It has been quite widely used in New Zealand since its introduction in 1993. The aim of this retrospective study was to provide an independent mid-term audit of the results of this cup in the New Zealand population. A retrospective review was undertaken of all Morscher cups implanted at Dunedin Public Hospital or Mercy Hospital by 5 orthopaedic surgeons between 1994 and 1998 with a minimum follow-up of seven years. Clinical and radiological survey was performed with standardised scoring systems. A new method for measuring linear cup wear was developed due to the unusual geometry of the Morscher cup. 136 hips were replaced in 121 patients during the study period 101 were performed in private and 35 in public. Our follow up ranged from 7 to 11 years (mean 8.69). There were 73 males (85 hips) and 48 females (51 hips). The average age of the patients was 57.5yrs (SO 24.97). Pre operatively the mean Merle d’Aubigne score was 9.4 (SO 4.02) and post operatively it was 17.4 (SO 1.58 (p<
0.0001). There were 2 early revisions: one at 3 days for instability post-operatively and one for an unrecognised intra-operative femoral fracture. One hip required a two stage revision for deep infection at 3 years. Two hips have been revised for polyethylene wear and osteolysis at 7 yrs and 9 yrs and one hip required bone grafting of a large acetabular osteolytic lesion with retention of the cup. A further 4 patients have significant osteolytic defects and 2 have minor osteolytic lesions. Wear measurements in the unrevised hips have shown a mean linear wear rate of 0.079mm/yr (range 0.000 to 0.222mm). 33% of these hips have a wear rate of >
0.1 mm/yr and 25% have a wear rate of <
0.05mm/yr. We have found excellent clinical results with the use of the Morscher cup in this relatively young and active cohort. A small group of patients, however, have shown higher wear rates or osteolysis, and we emphasise the importance of continuing radiological review.
The aim of this study was to determine the inter and intra observer reliability of ultrasound measurements in treated unstable neonatal hips and whether ultrasound measurements correlate with radiological outcome at 6 months. Sixty-four babies treated from birth with a Pavlik harness for neonatal hip instability were scanned at 2 and 6 weeks. The α and β angles of Graf, the combined (H) angle of Hosny and the femoral head coverage (FHC) were measured by 3 observers and inter-observer and intra-observer repeatability co-efficients calculated using 95% confidence limits. Hips were categorized as normal, abnormal or borderline for each parameter and Kappa values calculated. A stepwise linear regression analysis was performed to assess any relationship between ultrasound measurements at 2 or 6 weeks and outcome as determined by acetabular index at 6 months. Seven hundred and ninety two sets of measurements were made from 248 scans. The α angle had the smallest interobserver range (17°), the H angle range was 21°and the β angle 28°. Kappa values showed good agreement for FHC and β angle. The mean acetabular index of all hips at 6 months was 26° (sd 4.9). The acetabular index was 30° or greater in 24 hips (18 babies) despite prolonged splintage in 9 hips (6 babies). The FHC at 6 weeks was predictive of acetabular index at 6 months (regression coefficient −0.27, 95% CI −0.42 to −0.12, p<
0.001) We recommend the FHC as being reproducible, useful and predictive of outcome in neonatal hips treated for instability.
The aim was to compare the initial pull out strengths of various interference screw devices used for tibial fixation of hamstring grafts and the effect of concentric or eccentric screw position. Quadrupled tendon grafts were harvested from freshly killed sheep. The grafts were then prepared and fixed in the distal femur using various devices (Intrafix, RCI screw, Wedge screw +/− transfix pin, screw and post) in both concentric and eccentric positions. A single load to failure test was then performed. The highest pull out strength was with the Intrafix device inserted concentrically (mean 941N). This was significantly higher than the wedge screw inserted concentrically (737N) (p=0.015). This in turn had significantly greater initial pull out strength than the wedge eccentric with post or pin (p=0.03) and the RCI screw (464N) (p=0.00036). In this sheep model the Intrafix device inserted concentrically had a significantly greater initial pull-out strength than the other interference screws tested. Concentric positioning of an interference screw gave significantly greater initial pullout strength of a quadruple hamstring graft than eccentric positioning. Addition of a cross pin or post made no difference to initial pullout strength.
The aim was to audit the numbers of non-residents requiring orthopaedic admission to our hospital and determine the effect of increasing tourist numbers and changes in Accident Compensation Corporation (ACC) regulations on health care resources. Details of non-resident orthopaedic admissions for fiscal years 1997/8 to 2003/4 were analysed with respect to country of residence, mechanism of injury, case weights consumed and actual costs. There has been no change in numbers of admissions or cost averaging 32 cases (50 case weights) per year over the 7 year period. Most patients came from Asia (59 cases, 26%), then Australia (52 cases, 23%) and UK (40 cases 18%). Snowsports accounted for 40% of admissions, Motor vehicle accidents (MVA)17% and falls 29%. Non-resident, non-MVA admissions have averaged 21 CW per year since the changes in ACC regulations in 1999. Despite increasing tourist numbers there has been no increase in numbers or CW of non-residents requiring orthopaedic admission. Although representing only a small proportion of the orthopaedic budget they generate many hidden costs. The 50 CW annually equates to approximately 13 major joint replacements per year. The increase in CWs consumed due to the ACC changes have had no corresponding increase in contracted orthopaedic volumes.
The aim of this study was to prospectively audit the results of carpal tunnel decompression using a subjective patient derived outcome score (modified Boston Symptom Severity Score) and to examine the relationship between symptom severity scores and nerve conduction studies. Prospective cohort study of all patients undergoing open carpal tunnel decompression at Dunedin Hospital over a 13-month period from December 2003 – January 2005. Demographic details collected included age, sex, duration of symptoms, diabetes, occupation and ACC status. Pre-operative investigations consisted of nerve conduction studies and a modified version of the Boston Symptom Severity Score developed for this study. Symptom severity scores were reassessed six months post-operatively. One hundred and ten patients participated in the study. Mean pre-operative Boston Symptom Severity Score was 3.35 (1= normal, 5=severe). Post-operatively this improved to mean 1.66, median 1.45. Ninety three percent of patients were “very satisfied” or “satisfied” with their results. Age and duration of symptoms were not significant predictors of poor outcome. The majority of patients undergoing carpal tunnel decompression were satisfied with the outcome and had excellent or good outcomes as determined by symptom severity score. The use of preoperative nerve conduction studies help in diagnosis and prognosis.
We report early major complications encountered following TEN fixation of femoral fractures in children. A case series of four children aged 8– 16 years who had primary TEN fixation of isolated femoral diaphyseal fractures. Three of the four patients had major complications. These were: significant knee stiffness requiring manipulation, haemarthrosis requiring washout and nail removal, loss of position and refracture. Two required revision to locked intramedullary nails without early complication. In the skeletally immature child TEN fixation of femoral fractures has a significant major complication rate. This needs to be recognised when comparing TEN fixation with other treatment options.
We report intermediate term results of a technique of acetabular augmentation using block femoral head autograft and the uncemented expansion cup for adult hip dysplasia. A retrospective review of one surgeon (BFH) series of consecutive total hip replacements for hip dysplasia using femoral head acetabular augmentation was carried out. The technique involves sectioning the femoral head longitudinally reversing and fixing it to the deficient acetabulum with 6.5mm AO screws. This is then reamed to accept the uncemented expansion cup. Patients were identified from audit databases. Patients completed clinical questionnaires, examination and radiographic evaluation. Fifteen hips were identified in twelve patients (three bilateral). The average at age at surgery was 54 (44–58) years. There were eight females (eleven hips). Three patients (three hips) were unable to be contacted. Average follow up was 8.4 (4.8–11.4) years. Preoperative centre edge angle was 14 (−10–30) degrees. One patient developed a deep infection requiring early staged revision. One patient was not satisfied with her results at follow up. Mean Harris Hip Score was 83 (63–100), mean WOMAC Score was 76 (50–95). Range of motion was well maintained in all patients. Four patients had other co-morbidities affecting their results. Radiological review shows all grafts to have united with no screw breakage and no cup loosening. At eight year follow up there is high satisfaction, good clinical and radiological results. These results demonstrate good intermediate term results using this technique in total hip replacement with acetabular dysplasia.
The aim of this study was to determine the outcome of carpal tunnel decompression in elderly patients and whether this can be predicted by the severity of pre-operative nerve conduction studies. A retrospective study was undertaken of all patients over 70 years who had carpal tunnel release (CTR) at Dunedin Hospital between April 1999 and April 2002 with a minimum one year follow up. A grading system for pre-operative nerve conduction studies (NCS) was formulated which scored patients from 1 to 6 according to severity. Patients were followed up by postal questionnaire (Boston Carpal Tunnel Score) with telephone follow up of non-responders. There were 105 CTR procedures performed in 96 patients. Median pre-operative NCS Score was 4 with 47% scoring 5 or 6. 4 Patients had died. Post-operative symptom severity scores were low and the majority of patients were very satisfied with the results of surgery. Despite nerve conduction studies consistent with severe median nerve compression, patients had low postoperative symptom severity scores and overall were very satisfied. Carpal tunnel release in patients over 70 years of age is justified and associated with good outcome.
We compared initial fixation strength of two commonly used tibial side hamstring ACL reconstruction fixation implants – the RCI interference screw and the Intrafix device. Using a sheep model 36 hamstring grafts were prepared and implanted into the distal femoral metaphyseal bone using either a RCI screw or an Intrafix device. They were then pulled out until failure using an Instron Materials Testing Machine. Maximum strength of graft fixation and mode of failure were recorded. The average strength of the graft was 48kg using the RCI screw and 90 kg using the Intrafix device. This difference was statistically significant. The maximum pull-out strength was 91kg for the RCI screw and 130 kg for the Intrafix device. The most common mode of failure in the RCI screw fixation was graft shredding on the screw and whole graft pullout whereas in the Intrafix device it was intratendinous failure. The Intrafix device demonstrated a clear strength advantage over the RCI screw with regard to initial fixation strength. The Intrafix device may reduce tibial side graft creep which is a problem with hamstring ACL reconstruction.
The aim of this surgery was to determine current practice amongst orthopaedic surgeons in New Zealand with regard to Anterior Cruciate Ligament Reconstruction. All current members of the NZOA were sent a questionnaire on the numbers and proportions of grafts performed, methods of fixation, operative technique and return to sport. One hundred and ten of 140 questionnaires were returned completed. Ninety two orthopaedic surgeons were performing ACL reconstructions. Eight per cent performed patellar tendon grafts in preference to hamstring grafts, whereas 16% preferred hamstring over patellar tendon grafts. Almost 2000 patellar tendon grafts at an average of just over 20 per surgeon are performed each year compared to just over 500 hamstring grafts at an average of just over 15 per surgeon. Metal interference screws were the most common fixation device in patellar tendon and hamstring grafts. Patellar tendon grafts are the most common grafts used for ACL reconstruction with 80 % of those surveyed preferring to use patellar tendon over hamstring grafts. Metal interference screws were the most common fixation device. There is reasonable consensus regarding return to activity and sport.
To determine whether increased sagittal laxity has an effect on functional outcome following posterior cruciate retaining total knee replacement using two differing tibial insert designs. Ninety-seven patients were reviewed clinically, radiologically and underwent KT1000 testing of their TKR at a minimum follow up of 5 years (mean 6.5 yrs). The femoral component design was the same in all patients (Duracon/PCA). Fifty two patients had a relatively flat tibial insert design (group 1), while 45 patients had an AP lipped insert (group 2) following a change in design in 1995. The 2 groups were comparable for age, sex, Charnley category, BMI, tibial slope and follow up. There was no significant difference in laxity measurements, IKS or WOMAC scores between the groups. There was no significant correlation between laxity and outcome score or flexion range. Increased sagittal laxity in a knee replacement does not have a strong influence on functional outcome. The differing tibial insert designs had no significant effect on either laxity or function.
