Introduction/aims

Carpal tunnel decompression is common at the world's largest lamb processing plant. The purpose of this study was to establish whether lamb boning caused carpal tunnel syndrome, whether expeditious rehabilitation was possible and current New Zealand Orthopaedic practice.

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.

Carpal tunnel syndrome requiring decompression is common at the world’s largest lamb processing plant. However there is little to guide us in advising patients on return to heavy manual work postoperatively. The purpose of this study was to establish current New Zealand practice and whether expeditious return to work was possible.

Following informed consent a retrospective review of those with neurophysiologically-confirmed carpal tunnel syndrome requiring decompression over four seasons was performed. Open, day-case surgery was performed in all cases by the senior author. Patient demographics, time to return to work, further absenteeism, pain-free interval and complications were examined. A prospective study in the subsequent season was then performed. Additional information gathered for previous seasons pre and 6 week postoperatively included QuickDASH, SF36, grip-strength visual analogue pain, paraesthesiae and numbness scores. Student’s t-test was used for statistical analysis. An email survey of the NZOA was also performed.

One hundred percent follow-up was achieved. In the retrospective group 281 in 187 patients were performed. The average time to return to light duties/rehabilitation was 11 (9 – 42) days. The mean pain free interval was 24 (10 – 63) days. Return to full-duties was on average 28 (10 – 70) dayswith three patients (1% of the total cohort) requiring further time off. Ninety-nine percent returned to their previous role. There were two infections. In the prospective group in this study, 26 hands underwent decompression in 13 patients. The average return to light duties/rehabilitation was 13 (10–25) days and to full duties 32 (21–56) days. Ninety-two percent returned to their previous role and there was one superficial infect ion. The improvement in mean total QuickDASH scores (total score possible 300) were from 140 points (standard deviation 63: 95% CI 101–178) to 68 (standard deviation 54; 95% CI 34–100) and this was statistically significant (p< 0.01). The difference in Short Form 36 scores was not statistically significant (p = 0.6). The differences in numbness, pain and paraesthesiae visual analogue scores were all statistically significant at 6 weeks after surgery (p< 0.01, p< 0.01 and p=0.01 respectively). All patients felt that the operation had been overall worthwhile and at the time of submission none had taken any further time off work. Examining lamb boners as a separate group and using Survival and Cox regression analysis the average return to full working duties for lamb boners was 29 days which is significantly different to New Zealand Orthopaedic surgical practice.

The unique population at this plant has allowed a culture to develop whereby early return to light duties after removal of sutures is expected. This culture, good patient education, and coordinated efforts at all levels of the care pathway are undoubtedly necessary for this level of achievement.

Aim: To demonstrate the pattern and mechanism of injury of alpine skiing and snowboarding, and to evaluate the potential risk factors.

Methods: We analysed prospectively all cases of orthopaedic injuries requiring hospital admission that were the result of snowboarding or skiing accidents in the winter of 2000. This included four popular skiing facilities in the South Island of New Zealand.

Results: Seventy-six patients were reviewed. Of those, 30 cases were the results of accidents from snowboarding and 44 cases were from skiing. In addition to appropriate medical evaluations and medical care, a detailed examination was performed on every patient to determine various factors, including demographics, their level of experience and the cause and mechanism of the accident. There were 47 males and 29 females, with an average age of 28 (range: seven to 62)years. Snowboarders tended to be younger men with an average age of 23 years compared with 31 years in skiers. Males constituted 77% of snowboarders and 54% of skiers.

There were 14 patients in the beginners’ group, 32 intermediate, 20 advanced and nine at an extreme-skill level. Thirty-eight patients sustained injuries of the lower extremities, 24 of the upper extremities, 13 of the spine, and one of the pelvis. Lower extremity injuries were more common in skiers (59% of lower limbs, versus 25% of upper limbs), while in snow boarding upper extremity injuries were more common (43% upper limbs versus 36% lower limbs). Ulnar collateral ligament injuries of the metacarpophalangeal joint of the thumb, were far more common in skiers (six in skiers versus one on snowboard). Sixteen patients (nine skiers and six snow-boarders) sustained diaphyseal fractures of their tibiae. In all nine patients in the skiing group, the mechanism of injury was failure of the binding to release resulting in a twisting force to the leg, while in the snowboarding group, three patients (50%) fractured their tibiae on landing badly from a jump and in the other three on colliding with another person or a fixed object.

Conclusions: Lower extremity, equipment-related injuries are common in alpine skiing. The data suggested that currently used bindings are insufficient. Research, technical developments and optimal adjustment of binding are required.