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Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_3 | Pages 2 - 2
23 Feb 2023
Roffe L Peterson R Smith G Penumarthy R Atkinson N Ross M Singelton L Bodian C Timoko-Barnes S
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Trauma and elective orthopaedic demands in New Zealand are increasing. In this study, prospective and retrospective data has been collected at Nelson Hospital and across New Zealand to identify the percentage of elective theatre time lost due to cancellation for acute patient care. Data has been collected from theatre management systems, hospital data systems and logged against secretarial case bookings, to calculate a percentage of elective theatre time lost to acute operating or insufficient bed capacity.

Data was collected over a five-month period at Nelson Hospital, with a total of 215 elective and 226 acute orthopaedic procedures completed. A total of 95 primary hip or knee arthroplasties were completed during this trial while 53 were cancelled. The total number of elective operative sessions (one session is the equivalent of a half day operating theatre time) lost to acute workload was 47.9. Thirty-three percent of allocated elective theatre time was cancelled - an equivalent of approximately one-full day elective operating per week.

Over a five-week period data was collected across all provincial hospitals in New Zealand, with an average of 18% of elective operating time per week lost due to acute workload. Elective cancellations were due to acute operating 40% of the time and bed shortages 60% of the time. The worst effected centre was Palmerston North which had an average of 33% of elective operating cancelled per week to accommodate acute surgery or due to bed shortages.

New Zealand's provincial orthopaedic surgeons are under immense pressure from acute operating that impedes provision of elective surgery. The New Zealand government definition of an ‘acute case’ does not reflect the nature of today's orthopaedic burden. Increasing and aging populations along with staff and infrastructure shortages have financial and societal impacts beyond medicine and require better definitions, further research, and funding from governance.


Orthopaedic Proceedings
Vol. 105-B, Issue SUPP_2 | Pages 112 - 112
10 Feb 2023
Ross M Vince K Hoskins W
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Constrained implants with intra-medullary fixation are expedient for complex TKA. Constraint is associated with loosening, but can correction of deformity mitigate risk of loosening?

Primary TKA's with a non-linked constrained prosthesis from 2010-2018 were identified. Indications were ligamentous instability or intra-medullary fixation to bypass stress risers. All included fully cemented 30mm stem extensions on tibia and femur. If soft tissue stability was achieved, a posterior stabilized (PS) tibial insert was selected.

Pre and post TKA full length radiographs showed.

hip-knee-ankle angles (HKAA)

Kennedy Zone (KZ) where hip to ankle vector crosses knee joint.

77 TKA's in 68 patients, average age 69.3 years (41-89.5) with OA (65%) post-trauma (24.5%) and inflammatory arthropathy (10.5%).

Pre-op radiographs (62 knees) showed varus in 37.0% (HKAA: 4o-29o), valgus in 59.6% (HKAA range 8o-41o) and 2 knees in neutral.

13 cases deceased within 2 years were excluded. Six with 2 year follow up pending have not been revised. Mean follow-up is 6.1 yrs (2.4-11.9yrs).

Long post-op radiographs showed 34 (57.6%) in central KZ (HKKA 180o +/- 2o).

Thirteen (22.0%) were in mechanical varus (HKAA 3o-15o) and 12 (20.3%) in mechanical valgus: HKAA (171o-178o)

Three failed with infection; 2 after ORIF and one with BMI>50. The greatest post op varus suffered peri-prosthetic fracture. There was no aseptic loosening or instability.

Only full-length radiographs accurately measure alignment and very few similar studies exist. No cases failed by loosening or instability, but PPF followed persistent malalignment. Infection complicated prior ORIF and elevated BMI.

This does not endorse indiscriminate use of mechanically constrained knee prostheses. Lower demand patients with complex arthropathy, especially severe deformity, benefit from fully cemented, non-linked constrained prostheses, with intra-medullary fixation. Hinges are not necessarily indicated, and rotational constraint does not lead to loosening.


Orthopaedic Proceedings
Vol. 99-B, Issue SUPP_4 | Pages 16 - 16
1 Feb 2017
Hippensteel E Wise C Ross M Langhorn J Narayan V
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INTRODUCTION

Multiple sources have consistently reported oxidation indices less than 0.1 with Marathon® inserts implanted up to 10 years. Understanding effects of oxidation level on UHMWPE wear in vivo is of great value. The objective of this study is to characterize the wear performance of Marathon® acetabular inserts at various levels of artificially induced oxidation, quantified using Bulk Oxidation Index (BOI) as determined per ASTM F2102, and to ascertain if wear rate is affected by progressive polyethylene oxidation.

METHODS

GUR 1050 UHMWPE acetabular inserts, re-melted and cross-linked at 5.0Mrad (Marathon®, DePuy Synthes Joint Reconstruction, Warsaw, IN), were artificially aged per ASTM F-2003 in a stainless steel chamber at 5 atm. oxygen pressure and 70°C. Samples were maintained at temperature for 9, 10.4 and 11 weeks. After aging was completed, Fourier Transform Infra-Red (FTIR) spectroscopy was employed on one insert from each time point to evaluate the induced oxidation as a result of artificial aging. Resulting induced BOI values measured by FTIR were 0.195, 0.528 and 1.184. UHMWPE inserts had an inner diameter of 28mm and an outer diameter of 48mm and were articulated against 28mm diameter M-Spec® metal femoral heads (DePuy Synthes Joint Reconstruction, Warsaw, IN). Testing was conducted on a 12-station AMTI ADL hip simulator (AMTI, Watertown, MA) with load soak controls per ISO 14242-1:2014(E) in bovine serum (18mg/mL total protein concentration) supplemented with 0.056% sodium azide (preservative) and 5.56mM EDTA (calcium stabilizer). The UHMWPE inserts were removed from the machine, cleaned, and gravimetric wear determined per ISO 14242-2:2000(E) every 0.5 million cycles (MCyc) for 4.0 MCyc total. A two-tailed student's t-test was used (variance determined by F-test results) to analyze differences in wear rates between the three test groups.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_III | Pages 334 - 335
1 Sep 2005
Roberts C Duke P Mitchell M Ross M
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Introduction and Aims: Distal biceps ruptures are an uncommon injury. They represent approximately three percent of all biceps ruptures. Intervention was popularised by Boyd and Anderson who described a two-incision technique. Improved outcome has been achieved with stronger fixation allowing early mobilisation.

Method: All patients who underwent operative fixation of distal biceps ruptures by the senior two authors were identified. All patients were clinically reviewed at a minimum of six months from surgery. Functional outcomes scores in the form of Patient Rated Elbow Evaluation (PREE) and DASH scores were assessed. The operative technique utilised the Endobutton (Smith and Nephew) and is a substantial modification of that published by Bain,G et al.

Results: Thirty-one patients were identified. All patients were male with an average age of 47 years. Average delay to surgery was 24 days. There were no postoperative complications and no repeat ruptures. Thirty patients have returned Patient Rated Elbow Evaluation (PREE) forms with an average score of eight. Cybex testing demonstrates good return of strength when compared to the uninjured side.

Conclusion: Fixation of distal biceps ruptures using this modified Endobutton technique is a safe and effective method.


Orthopaedic Proceedings
Vol. 87-B, Issue SUPP_III | Pages 328 - 328
1 Sep 2005
Couzens G Hussain N Gilpin D Ross M
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Introduction and Aims: Unilateral joint destruction in small joints of the hand presents a difficult challenge, particularly in younger patients. Pyrocarbon has a number of properties which may render it more suitable than metal for hemiarthroplasty in selected circumstances. We reviewed the results of our experience with PIP and MCP hemiarthroplasty utilising pyrocarbon implants to evaluate the clinical outcome in each case.

Method: Since December 2001, 10 pyrocarbon hemiarthroplasties were implanted in 10 patients. Eight were implanted into the PIP joint and two into the MCP joint. The average patient age was 34.5 years (range 19–65). Nine procedures were for trauma and one for arthrosis. The decision to implant was taken when other reconstructive options were not considered possible and the patient would otherwise have been offered arthrodesis or amputation or total joint arthroplasty. The patients were reviewed clinically to establish their range of motion, pain control and satisfaction with surgery. Radiographic review was undertaken.

Results: After an average follow-up of 13 months (range three to 23 months) all joints remain in-situ. The average arc of motion is 50.5 degrees. Average extension was minus eight degrees (range 0–20) and average flexion was 58.5 (range 15–90). There was no evidence of loosening. Erosion of the intact side of the joint was noted in only one patient. One patient was not satisfied with the final outcome.

Conclusion: The short-term results of PIP and MCP hemiarthroplasty with a pyrocarbon prosthesis show reasonable promise and this procedure merits further evaluation of its role in the treatment of unilateral joint destruction. It may be preferable to either total joint arthroplasty or fusion, particularly in the younger patient.