Introduction

The purpose of this study was to compare implant survivorship and functional outcomes in patients undergoing reverse total shoulder arthroplasty (RTSA) for acute proximal humeral fracture (PHF) with those undergoing elective RTSA in a population-based cohort study.

Re-rupture rates after rotator cuff repair remain high because of inadequate biological healing at the tendon-bone interface. Single-growth factor therapies to augment healing at the enthesis have so far yielded inconsistent results. An emerging approach is to combine multiple growth factors over a spatiotemporal distribution that mimics normal healing. We propose a novel combination treatment of insulin-like growth factor 1 (IGF-1), transforming growth factor β1 (TGF-β1) and parathyroid hormone (PTH) incorporated into a controlled-release tyraminated poly-vinyl-alcohol hydrogel to improve healing after rotator cuff repair. We aimed to evaluate this growth factor treatment in a rat chronic rotator cuff tear model.

A total of 30 male Sprague-Dawley rats underwent unilateral supraspinatus tenotomy. Delayed rotator cuff repairs were then performed after 3 weeks, to allow tendon degeneration that resembles the human clinical scenario. Animals were randomly assigned to: [1] a control group with repair alone; or [2] a treatment group in which the hydrogel was applied at the repair site. All animals were euthanized 12 weeks after rotator cuff surgery and the explanted shoulders were analyzed for biomechanical strength and histological quality of healing at the repair site.

In the treatment group had significantly higher stress at failure (73% improvement, P=0.003) and Young's modulus (56% improvement, P=0.028) compared to the control group. Histological assessment revealed improved healing with significantly higher overall histological scores (10.1 of 15 vs 6.55 of 15, P=0.032), and lower inflammation and vascularity.

This novel combination growth factor treatment improved the quality of healing and strength of the repaired enthesis in a chronic rotator cuff tear model. Further optimization and tailoring of the growth factors hydrogel is required prior to consideration for clinical use in the treatment of rotator cuff tears. This novel treatment approach holds promise for improving biological healing of this clinically challenging problem.

Obesity is associated with poor outcomes and increased risk of failure after rotator cuff (RC) repair surgery. The effect of diet-induced obesity (DIO) on enthesis healing has not been well characterised and whether its effects can be reversed with dietary intervention is unknown. We hypothesised that DIO would result in inferior enthesis healing in a rat model of RC repair and that dietary intervention in the peri-operative period would improve enthesis healing.

A total of 78 male Sprague-Dawley rats were divided into three weight-matched groups from weaning and fed either: control diet (CD), high-fat diet (HFD), or HFD until surgery, then CD thereafter (HF-CD). After 12 weeks the left supraspinatus tendon was detached, followed by immediate surgical repair. At 2 and 12 weeks post-surgery, animals were cullers and RCs harvested for biomechanical and histological evaluation. Body composition and metabolic markers were assessed via DEXA and plasma analyses, respectively.

DIO was established in the HFD and HF-CD groups prior to surgery, and subsequently reversed in the HF-CD group after surgery. At 12 weeks post-surgery, plasma leptin concentrations were higher in the HFD group compared to the CD group (5.28 vs. 2.91ng/ml, P=0.003). Histologically, the appearance of the repaired entheses was poorer in both the HFD and HF-CD compared to the CD group at 12 weeks (overall histological score 6.20 (P=0.008), 4.98 (P=0.001) and 8.68 out of 15, respectively). The repaired entheses in the HF-CD group had significantly lower (26.4 N, P=0.028) load-at-failure 12 weeks post-surgery compared to the CD group (34.4 N); while the HFD group was low, but not significantly different (28.1 N, P=0.096). Body mass at the time of surgery, plasma leptin and body fat percentage were negatively correlated with histological scores and plasma leptin with load-at-failure 12 weeks post-surgery.

DIO impaired enthesis healing in this rat RC repair model, with inferior biomechanical and histological outcomes. Restoring normal weight with dietary change after surgery did not improve healing outcomes. Exploring interventions that improve the metabolic state of obese patients and counselling patients appropriately about their modest expectations after repair should be considered.

The optimal timing of when to perform manipulation under anesthesia (MUA) for stiffness following total knee arthroplasty (TKA) is unclear. This study aimed to identify the risk factors for MUA following primary TKA and whether performing an “early” MUA within 3 months results in a greater improvement in range of motion.

Primary TKAs performed between January 2013 and December 2018 at three tertiary New Zealand hospitals were reviewed. International Classification of Diseases discharge coding was used to identify patients who underwent an MUA. Multivariate Cox regression was performed to identify patient and surgical risk factors for MUA. Pre- and post-MUA knee flexion angles were identified through manual review of operation notes. Multivariate linear regression was performed to compare the mean flexion angles pre- and post-MUA, as well as the mean gain in flexion, between patients undergoing “early” (<3 months) versus “late” MUA (>3 months).

7386 primary TKAs were analyzed in which 131 underwent subsequent MUA (1.8%). Patients aged <65 years were two times more likely to undergo MUA compared to patients aged ≥65 years (2.5% versus 1.3%, adjusted hazard ratio = 2.1, p<0.001). Gender, body mass index, patient comorbidities or a history of cancer were not associated with the risk of MUA. There was no difference in the final post-MUA flexion angle between patients who underwent early versus late MUA (104.7 versus 104.1 degrees, p = 0.819). However, patients who underwent early MUA had poorer pre-MUA flexion (72.3 versus 79.6 degrees, p = 0.012), and subsequently had a greater overall gain in flexion compared to patients who underwent late MUA (mean gain 33.1 versus 24.3 degrees, p<0.001).

Younger age was the only patient risk factor for MUA. A greater overall gain in flexion was achieved in patients who underwent early MUA within 3 months.

Traumatic rotator cuff injuries can be a leading cause of prolonged shoulder pain and disability, and contribute to significant morbidity and healthcare costs. Previous studies have shown evidence of socio-demographic disparities with these injuries. The purpose of this nationwide study was to better understand these disparities based on ethnicity, sex, and socio-economic status, in order to inform future healthcare strategies.

Accident Compensation Corporation (ACC) is a no-fault comprehensive compensation scheme encompassing all of Aotearoa/New Zealand (population in 2018, 4.7 million). Using the ACC database, traumatic rotator cuff injuries were identified between January 2010 and December 2018. Injuries were categorized by sex, ethnicity, age and socioeconomic deprivation index of the claimant.

During the 9-year study period, there were 351,554 claims accepted for traumatic rotator cuff injury, which totalled over $960 million New Zealand Dollars. The greatest proportion of costs was spent on vocational support (49.8%), then surgery (26.3%), rehabilitation (13.1%), radiology (8.1%), general practitioner (1.6%) and “Other” (1.1%). Asian, Māori (Indigenous New Zealanders), and Pacific peoples were under-represented in the age-standardized proportion of total claims and had lower rates of surgery than Europeans. Māori had higher proportion of costs spent on vocational support and lower proportions spent on radiology, rehabilitation and surgery than Europeans. Males had higher number and costs of claims and were more likely to have surgery than females. There were considerably fewer claims from areas of high socio-economic deprivation.

This large nation-wide study demonstrates the important and growing economic burden of rotator cuff injuries. Indirect costs, such as vocational supports, are a major contributor to the cost suggesting improving treatment and rehabilitation protocols would have the greatest economic impact. This study has also identified socio-demographic disparities which need to be addressed in order to achieve equity in health outcomes.

Source of the study: University of Auckland, Auckland, New Zealand

Unicompartmental knee arthroplasty (UKA) is effective for patients with isolated compartment osteoarthritis, however the procedure has higher revision rates. Long-term survivorship and accurate characterisation of revision reasons are limited by a lack of long-term data and standardised revision definitions. We aimed to identify survivorship, risk factors and revision reasons in a large UKA cohort with up to 20 years follow-up.

Patient, implant and revision details were recorded through clinical and radiological review for 2,137 consecutive patients undergoing primary medial UKA across Auckland, Canterbury, Counties Manukau and Waitematā DHB between 2000 and 2017. Revision reasons were determined from review of clinical, laboratory, and radiological records for each patient using a standardised protocol. To ensure complete follow-up data was cross-referenced with the New Zealand Joint Registry to identify patients undergoing subsequent revision outside the hospitals. Implant survival, revision risk and revision reasons were analysed using Cox proportional-hazards and competing risk analyses.

Implant survivorship at 15 years was comparable for cemented fixed-bearing (cemFB; 91%) and uncemented mobile-bearing (uncemMB; 91%), but lower for cemented mobile-bearing (cemMB; 80%) implants. There was higher incidence of aseptic loosening with cemented implants (3–4% vs. 0.4% uncemented, p<0.01), osteoarthritis (OA) progression with cemMB implants (9% vs. 3% cemFB/uncemMB; p<0.05) and bearing dislocations with uncemMB implants (3% vs. 2% cemMB, p=0.02). Compared with the oldest patients (≥75 years), there was a nearly two-fold increase in risk for those aged 55–64 (hazard ratio 1.9; confidence interval 1.1-3.3, p=0.03). No association was found with gender, BMI or ASA.

Cemented mobile-bearing implants and younger age were linked to lower implant survivorship. These were associated with disease progression and bearing dislocations. The use of cemented fixed-bearing and uncemented mobile-bearing designs have superior comparable long-term survivorship.

We hypothesised that diet-induced obesity (DIO) would result in inferior enthesis healing in a rat model of rotator cuff (RC) repair and that dietary intervention in the peri-operative period would improve enthesis healing.

A total of 78 male Sprague-Dawley rats were divided into three weight-matched groups from weaning and fed either: control diet (CD), high-fat diet (HFD), or HFD until surgery, then CD thereafter (HF-CD). After 12 weeks, the left supraspinatus tendon was detached, followed by immediate surgical repair. At 2 and 12 weeks post-surgery, animals were culled, and RCs harvested for biomechanical and histological evaluation. Body composition and metabolic markers were assessed via DEXA and plasma analyses, respectively.

DIO was established in the HFD and HF-CD groups before surgery and subsequently reversed in the HF-CD group after surgery. Histologically, the appearance of the repaired entheses was poorer in both the HFD and HF-CD groups compared with the CD group at 12 weeks after surgery, with semiquantitative scores of 6.2 (P<0.01), 4.98 (P<0.01), and 8.7 of 15, respectively. The repaired entheses in the HF-CD group had a significantly lower load to failure (P=0.03) at 12 weeks after surgery compared with the CD group, while the load to failure in the HFD group was low but not significantly different (P=0.10). Plasma leptin were negatively correlated with histology scores and load to failure at 12 weeks after surgery.

DIO impaired enthesis healing in this rat RC repair model, with inferior biomechanical and histological outcomes. Restoring normal weight with dietary change after surgery did not improve healing outcomes. Circulating levels of leptin significantly correlated with poor healing outcomes. This pre-clinical rodent model demonstrates that obesity is a potentially modifiable factor that impairs RC healing and increases the risk of failure after RC surgery.

Surgical repair of rotator cuff tears have high failure rates (20–70%), often due to a lack of biological healing. Augmenting repairs with extracellular matrix-based scaffolds is a common option for surgeons, although to date, no commercially available product has proven to be effective. In this study, a novel collagen scaffold was assessed for its efficacy in augmenting rotator cuff repair. The collagen scaffold was assessed in vitro for cytocompatability and retention of tenocyte phenotype using alamarBLUE assays, confocal imaging and real-time PCR. Immunogenicity was assessed in vitro by the activation of pre-macrophage cells. In vivo, using a modified rat rotator cuff defect model, supraspinatus tendon repairs were carried out in 46 animals. Overlay augmentation with the collagen scaffold was compared to unaugmented repairs. At 6- and 12-weeks post-op the repairs were tested biomechanically to evaluate repair strength, and histologically for quality of healing. The collagen scaffold supported human tenocyte growth in vitro, with cells appearing morphologically tenocytic and expressing higher tendon gene markers compared to plastic controls. No immunogenic responses were provoked compared to suture material control. In vivo, augmentation with the scaffold improved the histological scores at 12 weeks (8.37/15 vs. 6.43/15, p=0.0317). However, no significant difference was detected on mechanical testing. While the collagen scaffold improved the quality of healing of the tendon, a meaningful increase in biomechanical strength was not achieved. This is likely due to its inability to affect the bone-tendon junction. Future materials/orthobiologics must target both the repaired tendon and the regenerating bone-tendon junction.

Despite modern surgical techniques, reported rates of deep infection following Total Knee Replacement (TKR) persist between 1–2.5%. Coagulase-negative staphylococcus (CNS) has become the most common causative organism, and while growth of CNS is more indolent thanstaphylococcus aureus, it has a relatively higher minimum inhibitory concentration (MIC) against cephalosporins. Tissue concentrations of prophylactic antibiotics may fall below this level during TKR with conventional ‘systemic’ dosing.

Regional administration of prophylactic antibiotics via a foot vein following tourniquet inflation has been shown to provide tissue concentrations approximately 10 times higher than systemic dosing, however cannulation of a foot vein is difficult, time consuming, and may compromise sterility.

Intraosseous cannulation offers an alternative method of accessing the vascular system, and the aim of this study was to assess its effectiveness in administration of prophylactic antibiotics. 22 patients undergoing primary total knee arthroplasty were randomised into two groups. Group 1 received 1g of cephazolin systemically 10 minutes prior to tourniquet inflation. In Group 2 the EZ-IO tibial cannulation system was used, and 1g of cephazolin was administered intraosseously in 200ml of normal saline following tourniquet inflation and prior to skin incision. Subcutaneous fat and femoral bone samples were taken at set intervals during the procedure, and antibiotic concentrations measured using High Performance Liquid Chromatography (HPLC).

There were no significant differences in patient demographics, comorbidities, or physical parameters between groups. The overall mean tissue concentration of cephazolin in subcutaneous fat was 185.9μg/g in the intraosseous group and 10.6μg/g in the systemic group (p<0.01). The mean tissue concentration in bone was 129.9 μg/g in the intraosseous group and 11.4μg/g in the systemic group (p<0.01). These differences were consistent across all sample time points throughout the procedure. No complications occurred in either group.

Intraosseous regional administration can achieve tissue levels of antibiotic over an order of magnitude higher than systemic administration. Further work is required to determine if there is clinical benefit in preventing infection, particularly against CNS. This novel mode of drug administration may also have other applications, allowing ‘surgical site delivery’ of medication while minimising systemic side effects.

Background

Since its first description, the pathology, natural history and treatment of lateral epicondylitis have remained controversial. For those who fail conservative management, surgery remains an option. The optimal method of surgery remains debatable and is further confounded by a relative lack of long-term follow up studies.

Introduction and Aims: Several surgical techniques have been described for the treatment of resistant lateral epicondylitis or tennis elbow with variable results. This retrospective study presents the long-term outcome of a single surgeon’s experience, with a modified surgical technique for the treatment of resistant lateral epicondylitis.

Method: Between 1986 and 2001, the senior author performed 171 surgical procedures in 158 patients for resistant lateral epicondylitis. 147 elbows in 136 patients (88%) were independently evaluated at a mean time to follow-up of 9.8 years. Patients were assessed using a functional questionnaire and physical assessment. In addition to physical assessment, provocative testing of the extensor origin and grip strength was performed. Patients subjectively rated the result of surgery and these results were compared to objective elbow performance scores.

Results: Subjectively, 97% of patients assessed the result from surgery as good to excellent. Objectively, 97% results were good to excellent using elbow performance scores. Synovial fistulae developed in two patients by day 10 post-operatively. One patient required further surgery for a synovial fistula, which healed with no sequelae. There were no other complications following surgery. The post-operative range of motion improved in all patients, but remained reduced in four patients. There was a significantly worse outcome for patients with a Workers’ compensation claim and for cigarette smokers. There was no difference between grip strengths between the operated arm and the non-operated arm. The majority of patients returned to work by six weeks and were pain-free by 12 weeks. Less than 5% of patients experienced lateral epicondylitis pain in their elbow post-operatively. A small group of patients altered their occupation or recreational activities due to tennis elbow symptoms.

Conclusion: The surgical technique described produces excellent results in greater than 87% of patients in the treatment of resistant lateral epicondylitis. This procedure produces a low complication rate and is associated with a high rate of patient satisfaction. Patient selection is critical in the surgical treatment of resistant lateral epicondylitis.

Several surgical techniques have been described of resistant lateral epicondylitis or tennis elbow with variable results. This retrospective study presents the long-term outcome of a single surgeons experience with a modified surgical technique for the treatment of resistant lateral epicondylitis.

Between 1986 and 2001, the senior author performed 171 surgical procedures in 158 patients for resistant lateral epicondylitis. 147 elbows in 136 patients (88%) were independently evaluated at a mean time to follow up of 9.8 years. Patients were assessed using a functional questionnaire and physical assessment. In addition to physical assessment, provocative testing of the extensor origin and grip strength was performed. Patients subjectively rated the result of surgery and these results were compared to objective elbow performance scores.

Subjectively, 97% of patients assessed the result from surgery as good to excellent. Objectively, 97% results were good to excellent using elbow performance scores. Synovial fistulate developed in two patients by day ten postoperatively. One patient required further surgery for a synovial fistula which healed with no sequelae. There were no other complications following surgery. The postoperative range of motion improved in all patients but remained reduced in four patients. There was a significantly worse outcome for patients with Worker’s compensation claim and for cigarette smokers. There was no difference between grip strengths between the operated arm and the non-operated arm. The majority of patients returned to work by six weeks and were pain free by twelve weeks. Less than 5% of patients experienced lateral epicondylitis pain in their elbow post-operatively. A small group of patients altered their occupation or recreational activities due to tennis elbow symptoms.

The surgical technique described produces excellent results in greater than 87% of patients in the treatment of resistant lateral epicondylitis. This procedure produces a low complication rate and is associated with a high rate of patient satisfaction. Patient selection is critical in the surgical treatment of resistant lateral epicondylitis.

Aim: To study the complications of an extended lateral femoral osteotomy (after Paprosky) of the femur utilised for exposure in revision total hip replacement.

Method: A retrospective audit was performed of the senior author’s revision hip patients who had, at the time of surgery, an extended lateral femoral osteotomy for both deformity correction and to facilitate cement removal. No attempt was made to correlate the use of an osteotomy and operating time or overall results as no unbiased control group was available. The time to radiological union and complications of the procedure was reviewed to assess the safety of an osteotomy in one surgeon’s practice.

Results: Thirty patients with 31 osteotomies were reviewed, all with long-stem fully porous coated femoral stems. It was the senior author’s anecdotal opinion that osteotomy facilitated cement removal without canal perforation and was necessary for varus deformity correction in many patients. All osteotomies united without further procedures after an average of 22 weeks (range: 12 to 38 weeks). There was one fatigue fracture of the osteotomised fragment, one non-union of the greater trochanter and two cable failures; all without significant sequelae. There was one fracture of the medial proximal femur that required a period of four weeks of bed-rest; otherwise all patients were mobilised full weight bearing as tolerated. One patient had deep infection and a loose femoral component. Two patients had instability of the hip in the post-operative period.

Conclusion: We have shown that the osteotomy reliably united and was safe even with early full weight bearing, with few complications. Extended femoral osteotomy for deformity correction and cement removal in revision hip replacement is a safe and easy technique that reliably facilitates revision.