When removing femoral cement in revision hip surgery, creating an anterior femoral cortical window is an attractive alternative to extended trochanteric osteotomy. We describe our experience and evolution of this technique, the clinical and radiological results, and functional outcomes.

Between 2006 and 2021 we used this technique in 22 consecutive cases at Whanganui Hospital, New Zealand. The average age at surgery was 74 years (Range 44 to 89 years). 16 cases were for aseptic loosening: six cases for infection.

The technique has evolved to be more precise and since 2019 the combination of CT imaging and 3-D printing technology has allowed patient-specific (PSI) jigs to be created (6 cases). This technique now facilitates cement removal by potentiating exposure through an optimally sized anterior femoral window.

Bone incorporation of the cortical window and functional outcomes were assessed in 22 cases, using computer tomography and Oxford scores respectively at six months post revision surgery. Of the septic cases, five went onto successful stage two procedures, the other to a Girdlestone procedure.

On average, 80% bony incorporation of the cortical window occurred (range 40 −100%). The average Oxford hip score was 37 (range 22 – 48). Functional outcome (Oxford Hip) scores were available in 11 cases (9 pre-PSI jig and 2 using PSI jig). There were two cases with femoral component subsidence (1 using the PSI jig).

This case series has shown the effectiveness of removing a distal femoral cement mantle using an anterior femoral cortical window, now optimized by using a patient specific jig with subsequent reliable bony integration, and functional outcomes comparable with the mean score for revision hip procedures reported in the New Zealand Joint Registry.

The aim of this study was to compare the relative performance of total hip replacement constructs and discern if there is substantial variability in performance in currently commonly used prostheses.

All patients who underwent a primary total hip replacement (THR) registered in the NZJR between 1^st January 1999 to June 2020 were identified. Using a noninferiority analysis, the performance of hip prostheses were compared with the best performing contemporary construct. Construct failure was estimated using the 1-Kaplan Meier survival function method to estimate net failure. The difference in failure between the contemporary benchmark and other constructs was examined.

In total 135 432 THR were recorded comprising 1 035 different THR constructs. Notably 328 constructs were used just once. 48 constructs (62 251 THR) had >500 procedures at risk at 3 years post-primary of which 28 were inferior by at least 20% relative risk of which, 10 were inferior by at least 100% relative risk. 16 constructs were identified with >500 procedures at risk at 10 years with 9 inferior by at least 20%, of which one was inferior by >100% relative risk. There were fewer constructs noninferior to the best practice benchmark when we performed analysis by gender. In females at 10 years, from 5 constructs with >500 constructs at risk, 2 were inferior at the 20% margin. In males at 10 years, there were only 2 eligible constructs of which one was inferior at the 20% margin.

We discerned that there is substantial variability in construct performance and at most time points, just over half of constructs are inferior to the best performing construct by at least 20%. These results can facilitate informed decision-making when considering THR surgery.

Background

Reduced dislocation rates using lipped polyethylene (PE) liners in modular uncemented acetabular components has been shown, yet there may be increased wear because of impingement, which may lead to aseptic loosening. We used New Zealand Joint Registry (NZJR) data to compare survival rates, revision rates for dislocation and aseptic loosening between lipped and neutral liners.

Aims

A borderline dysplastic hip can behave as either stable or unstable and this makes surgical decision making challenging. While an unstable hip may be best treated by acetabular reorientation, stable hips can be treated arthroscopically. Several imaging parameters can help to identify the appropriate treatment, including the Femoro-Epiphyseal Acetabular Roof (FEAR) index, measured on plain radiographs. The aim of this study was to assess the reliability and the sensitivity of FEAR index on MRI compared with its radiological measurement.

Aims

The primary aim of this study was to define and quantify three new measurements to indicate the position of the greater trochanter. Secondary aims were to define ‘functional antetorsion’ as it relates to abductor function in populations both with and without torsional abnormality.

The definition of osseous instability in radiographic borderline dysplastic hips is difficult. A reliable radiographic tool that aids decision-making specifically, a tool that might be associated with instability-therefore would be very helpful for this group of patients. The aims of this study were:

(1) To compare a new radiographic measurement, which we call the Femoro-Epiphyseal Acetabular Roof (FEAR) index, with the lateral centre-edge angle (LCEA) and acetabular index (AI), with respect to intra- and interobserver reliability; (2) to correlate AI, neck-shaft angle, LCEA, iliocapsularis volume, femoral antetorsion, and FEAR index with the surgical treatment received instable and unstable borderline dysplastic hips; and (3) to assess whether the FEAR index is associated clinical instability in borderline dysplastic hips.

We defined and validated the FEAR index in 10 standardized radiographs of asymptomatic controls using two blinded independent observers. Interrater and intrarater coefficients were calculated, supplemented by Bland-Altman plots. We compared its reliability with LCEA and AI. We performed a case-control study using standardized radiographs of 39 surgically treated symptomatic borderline radiographically dysplastic hips and 20 age-matched controls with asymptomatic hips (a 2:1 ratio), the latter were patients attending our institution for trauma unrelated to their hips but who had standardized pelvic radiographs between January 1, 2016 and March 1, 2016.

Patient demographics were assessed using univariate Wilcoxon two-sample tests. There was no difference in mean age (overall: 31.5 ± 11.8 years [95% CI, 27.7–35.4 years]; stable borderline group: mean, 32.1± 13.3 years [95%CI, 25.5–38.7 years]; unstable borderline group: mean, 31.1 ± 10.7 years [95% CI, 26.2–35.9 years]; p = 0.96) among study groups. Treatment received was either a periacetabular osteotomy (if the hip was unstable) or, for patients with femoroacetabular impingement, either an open or arthroscopic femoroacetabular impingement procedure. The association of received treatment categories with the variables AI, neck-shaft angle, LCEA, iliocapsularis volume, femoral antetorsion, and FEAR index were evaluated first using Wilcoxon two-sample tests (two-sided) followed by stepwise multiple logistic regression analysis to identify the potential associated variables in a combined setting. Sensitivity, specificity, and receiver operator curves were calculated. The primary endpoint was the association between the FEAR index and instability, which we defined as migration of the femoral head either already visible on conventional radiographs or recentering of the head on AP abduction views, a break of Shenton's line, or the appearance of a crescent-shaped accumulation of gadolinium in the posteroinferior joint space at MR arthrography.

The FEAR index showed excellent intra- and interobserver reliability, superior to the AI and LCEA. The FEAR index was lower in the stable borderline group (mean, −2.1 ± 8.4; 95% CI, −6.3 to 2.0) compared with the unstable borderline group (mean, 13.3 ± 15.2; 95% CI, 6.2–20.4) (p < 0.001) and had the highest association with treatment received. A FEAR index less than 5° had a 79% probability of correctly assigning hips as stable and unstable, respectively (sensitivity 78%; specificity 80%).

A painful hip with a LCEA of 25° or less and FEAR index less than 5° is likely to be stable, and in such a situation, the diagnostic focus might more productively be directed toward femoroacetabular impingement.

Objectives

Effective analgesia after total knee arthroplasty (TKA) improves patient satisfaction, mobility and expedites discharge. This study assessed whether continuous femoral nerve infusion (CFNI) was superior to a single-shot femoral nerve block in primary TKA surgery completed under subarachnoid blockade including morphine.

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.

Aim

To assess the efficacy and ease of use of the Oxford Knee Score (OKS) in soft tissue knee pathology.

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.

Background. Patients with severe osteoarthritis of the knee often have to endure many months of pain and limited function whilst waiting for surgery. Measures that can improve quality of life and knee function while on waiting lists are worth employing and may improve post-operative recovery. This study was designed to evaluate the effects of standardised western acupuncture and supervised exercise therapy on pain control and functional ability in patients with severe osteoarthritic knee pain awaiting knee arthroplasty.

Methods. A three arm, single blind, randomised controlled trial was devised and took place at the Great Western Hospital, Swindon, UK. 181 patients awaiting knee arthroplasty met eligibility criteria and were entered into the trial. Block computerized randomisation was used to allocate patients to one of three treatment groups using a blinded third party. The three treatment groups were acupuncture for six weeks; supervised exercise therapy for six weeks or standardised advice. Outcome measures were assessed at 7 and 12 weeks following the initiation of treatment. The main outcome measures used were the Oxford Knee Score questionnaire, a 50 meter timed walk and duration of hospital stay following knee arthroplasty. Statistical analysis was performed with one way variance (ANOVA) analysis by intention to treat. Bonferroni method was used for analysis of statistically significant group differences.

Results. There was no baseline difference between groups. At 7 weeks there was a 10% reduction in Oxford Knee Score in the acupuncture group and a significant difference between the acupuncture and the other two groups: mean (SD) acupuncture 36.8 (7.2); physiotherapy 39.2 (8.2); control 40.3 (8.48) (p=0.0497). The supervised exercise group had a lower mean 50 meter walking time (50.3 seconds SD 17.7) compared to the acupuncture group (54.9 seconds SD 17) and the control group (58.4 seconds SD 25.2). Both these effects were still present but diminished at twelve weeks. There was a trend (p=0.0984) towards a shorter inpatient stay of one day for the physiotherapy group (mean 6.5 days SD 2.0) compared to the acupuncture group (mean 7.77 days SD 3.96).

Conclusions. Acupuncture can provide short-lived pain relief and improvement in function in patients with severe knee osteoarthritis awaiting knee arthroplasty. Supervised exercises lead to improvement in mobility. This functional improvement may decrease duration of hospital stay. Both interventions can be delivered safely and effectively in an outpatient group setting in a district general hospital and appear to be worthwhile for patients on the waiting list for surgery. Further evaluation of the effects of both treatments delivered simultaneously is planned.

Aim: To assess the Oxford Knee Score (OKS) for the assessment of soft tissue knee pathology?

Method: In a prospective study, we compared the OKS against the International Knee Documentation Committee (IKDC 2000) and the Lysholm Scores (Lys). We also assessed the OKS with retrograde and antegrade (as currently used in Oxford) numbering. All patients completed 3 questionnaires stating which was the simplest from their perspective. We recruited 73 patients from the orthopaedic and physiotherapy clinics, meeting the following criteria:

Results: Linear regression analysis revealed no significant difference between all 3 scores (R²=0.7823, P< 0.0001). The OKS correlated best with the IKDC (r=0.7483, Fig1), but less so with the Lys (r=0.3278, Fig2). The reversed OKS did not correlate as well (R²= 0.2603) with either the IKDC (r= −0.2978) or the Lys (r= −0.2586). ANOVA showed the OKS to be significantly easier than Lys to complete (p< 0.0001), but not significantly easier than IKDC (p> 0.05).

Conclusion: The OKS is patient friendly and reliable in assessing soft tissue knee injury. This is particularly useful if the OKS is already in use within a department for measurement of severity of degenerative disease.

Recent clinical studies have suggested that a neurological lesion may be a cause of adolescent idiopathic scoliosis and animal experiments have implicated the posterior column pathway. We have tried to determine if differences in neurological response could be detected and measured clinically, and have compared the threshold of detection of vibratory sensation in 20 girls with adolescent idiopathic scoliosis with that in 20 clinically normal age-matched controls. A highly significant reduction of the threshold of detection of vibration was seen in the scoliotic group compared to the controls (p less than 0.001). Curve magnitude did not correlate with this threshold for either the upper (r = 0.172) or lower extremity (r = 0.126). Significant asymmetry between right- and left-sided thresholds to vibration was demonstrated in the scoliotic group. Our study supports the concept that an aberration in the function of the posterior column pathway of the cord may be of primary importance in the aetiology of idiopathic scoliosis. A clinically practical test to measure this function is presented.