High in-vivo accuracy of a novel robotic-arm-assisted system for total knee arthroplasty

PURPOSE

Robotic-assisted total knee arthroplasty (TKA) has been shown to improve the accuracy and precision of bony resections and implant position. However, the in vivo accuracy of the full surgical workflow has not been widely reported. The primary objective of this study is to determine the accuracy and precision of a robotic-arm-assisted system throughout the intraoperative workflow.

METHODS

This was a retrospective cohort study of adult patients who underwent primary TKA with various workflows and alignment targets by three arthroplasty-trained surgeons with previous experience using the ROSA® Knee System (Zimmer Biomet) over a 3-month follow-up period. Accuracy and precision were determined by measuring the difference between various workflow time points, including the final preoperative plan (PP), robot-validated (RV) resection angle and postoperative radiographs (PR). The absolute mean difference between the measurements determined accuracy, and the standard deviation represented precision. The lateral distal femoral angle, medial proximal tibial angle, femoral flexion angle and tibial slope were measured on postoperative coronal long-leg radiographs and true short-leg lateral radiographs.

RESULTS

A total of 77 patients were included in the final analyses. The accuracy for the coronal femoral angle was 1.62 ± 1.11°, 0.75 ± 0.79° and 1.96 ± 1.29° for the differences between PP and PR, PP and RV and RV and PR. The tibial coronal accuracy was 1.44 ± 1.03°, 0.81 ± 0.67° and 1.57 ± 1.14° for PP/PR, PP/RV and RV/PR, respectively. Femoral flexion accuracy was 1.39 ± 1.05°, 0.83 ± 0.59° and 1.81 ± 1.21° for PP/PR, PP/RV and RV/PR, respectively. Tibial slope accuracy was 0.99 ± 0.72°, 1.19 ± 0.87° and 1.63 ± 1.11°, respectively. The proportion of patients within 3° was 93.2%, 95.3%, 97.3% and 94.6% for the distal femur, proximal tibia, femoral flexion and tibial slope angles when the final intraoperative plan was compared to PRs. No patients had a postoperative complication at the final follow-up.

CONCLUSIONS

The ROSA Knee System has acceptable accuracy and precision of coronal and sagittal plane resections with few outliers at various steps throughout the platform's entire workflow in vivo.

LEVEL OF EVIDENCE

Level III.

Elevated glucose promotes MMP13 and ADAMTS5 production by osteoarthritic chondrocytes under oxygenated but not hypoxic conditions

Type 2 diabetes is linked with increased incidence and severity of osteoarthritis. The purpose of this study was to determine the effect of extracellular glucose within the normal blood glucose and hyperglycemic range on catabolic enzyme production by chondrocytes isolated from osteoarthritic (OA) and macroscopically normal (MN) human cartilage under oxygenated (18.9% oxygen) and hypoxic (1% oxygen) conditions. OA and MN chondrocytes were maintained in 4, 6, 8, or 10 mM glucose for 24 h. Glucose consumption, GLUT1 glucose transporter levels, MMP13 and ADAMTS5 production, and levels of RUNX2, a transcriptional regulator of MMP13, ADAMTS5, and GLUT1, were assessed by enzyme-linked assays, RT-qPCR and/or western blot. Under oxygenated conditions, glucose consumption and GLUT1 protein levels were higher in OA but not MN chondrocytes in 10 mM glucose compared to 4 mM. Both RNA and protein levels of MMP13 and ADAMTS5 were also higher in OA but not MN chondrocytes in 10 mM compared to 4 mM glucose under oxygenated conditions. Expression of RUNX2 was overall lower in MN than OA chondrocytes and there was no consistent effect of extracellular glucose concentration on RUNX2 levels in MN chondrocytes. However, protein (but not RNA) levels of RUNX2 were elevated in OA chondrocytes maintained in 10 mM versus 4 mM glucose under oxygenated conditions. In contrast, neither RUNX2 levels or MMP13 or ADAMTS5 expression were increased in OA chondrocytes maintained in 10 mM compared to 4 mM glucose in hypoxia. Elevated extracellular glucose leads to increased glucose consumption and increased RUNX2 protein levels, promoting production of MMP13 and ADAMTS5 by OA chondrocytes in oxygenated but not hypoxic conditions. These findings suggest that hyperglycaemia may exacerbate chondrocyte-mediated cartilage catabolism in the oxygenated superficial zone of cartilage in vivo in patients with undertreated type 2 diabetes, contributing to increased OA severity.

Reverse total shoulder arthroplasty for acute proximal humeral fracture has comparable 10-year outcomes to elective indications: results from the New Zealand Joint Registry

HYPOTHESIS AND BACKGROUND

Recently, the indication of reverse total shoulder arthroplasty (RTSA) has expanded beyond rotator cuff arthropathy to include treatment of complex acute proximal humeral fracture (PHF). Limited previous studies have compared the long-term clinical and functional outcomes of patients undergoing RTSA for PHF vs. elective indications for degenerative conditions. The purpose of this study was to compare implant survivorship, reasons for revision and functional outcomes in patients undergoing RTSA for acute PHF with those undergoing elective RTSA in a population-based cohort study.

METHODS

Prospectively collected data from the New Zealand Joint Registry from 1999 to 2021 and identified 6862 patients who underwent RTSA. Patients were categorized by preoperative indication, including PHF (10.8%), rotator cuff arthropathy (RCA) (44.5%), osteoarthritis (OA) (34.1%), rheumatoid arthritis (RA) (5.5%), and old traumatic sequelae (5.1%). Revision-free implant survival and functional outcomes (Oxford Shoulder Scores [OSSs] at the 6-month, 5-year, and 10-year follow-ups) were adjusted by age, sex, American Society of Anesthesiologists class, and surgeon experience and compared.

RESULTS

Revision-free implant survival at 10 years for RTSA for PHF was 97.3%, compared with 96.1%, 93.7%, 92.8%, and 91.3% for OA, RCA, RA and traumatic sequelae, respectively. When compared with RTSA for PHF, the adjusted risk of revision was significantly higher for traumatic sequelae (hazard ratio = 2.3, P = .023) but not for other elective indications. The most common reason for revision in the PHF group was dislocation or instability (42.9%), which was similar to the OA (47.6%) and traumatic sequelae (33.3%) groups. At 6 months post-surgery, OSSs were significantly lower for the PHF group compared with the RCA, OA, and RA groups (31.1 vs. 35.6, 37.7, and 36.5, respectively, P < .001), and similar to traumatic sequelae (31.7, P = .431). At 5 years, OSSs were only significantly lower for PHF compared with OA (37.4 vs. 41.0, P < .001) and there was no difference between the PHF and other groups. At 10 years, there were no significant differences between groups.

CONCLUSIONS

RTSA for PHF demonstrated reliable long-term survivorship and functional outcomes compared with elective indications. Despite lower functional outcomes in the early postoperative period for the PHF group, implant survivorship was similar in patients undergoing RTSA for the primary indication of acute PHF compared with RCA, OA, and RA and superior compared to the primary indication of traumatic sequelae.

Characterization of adult human skeletal cells in different tissues reveals a CD90+CD34+ periosteal stem/progenitor population

The periosteum plays a crucial role in bone healing and is an important source of skeletal stem and progenitor cells. Recent studies in mice indicate that diverse populations of skeletal progenitors contribute to growth, homeostasis and healing. Information about the in vivo identity and diversity of skeletal stem and progenitor cells in different compartments of the adult human skeleton is limited. In this study, we compared non-hematopoietic populations in matched tissues from the femoral head and neck of 21 human participants using spectral flow cytometry of freshly isolated cells. High-dimensional clustering analysis indicated significant differences in marker distribution between periosteum, articular cartilage, endosteum and bone marrow populations, and identified populations that were highly enriched or unique to specific tissues. Periosteum-enriched markers included CD90 and CD34. Articular cartilage, which has very poor regenerative potential, showed enrichment of multiple markers, including the PDPN+CD73+CD164+CD146- population previously reported to represent human skeletal stem cells. We further characterized periosteal populations by combining CD90 with other strongly expressed markers. CD90+CD34+ cells sorted directly from periosteum showed significant colony-forming unit fibroblasts (CFU-F) enrichment, rapid expansion, and consistent multi-lineage differentiation of clonal populations in vitro. In situ, CD90+CD34+ cells include a perivascular population in the outer layer of the periosteum and non-perivascular cells closer to the bone surface. CD90+ cells are also highly enriched for CFU-F in bone marrow and endosteum, but not articular cartilage. In conclusion, our study indicates considerable diversity in the non-hematopoietic cell populations in different tissue compartments within the adult human skeleton, and suggests that periosteal progenitor cells reside within the CD90+CD34+ population.

Phenotype and energy metabolism differ between osteoarthritic chondrocytes from male compared to female patients: Implications for sexual dimorphism in osteoarthritis development?

OBJECTIVES

The prevalence and severity of knee osteoarthritis (OA) are greater in females than males. The purpose of this study was to determine whether there is an underlying difference in the biology of OA chondrocytes between males and females.

METHODS

Chondrocytes were obtained following knee arthroplasty from male and female patients with primary OA. Phenotype marker expression, glucose and fat consumption, and rates of glycolysis and oxidative phosphorylation were compared between females and males. RNAi was used to determine the consequences of differential expression of Sry-box transcription factor 9 (SOX9) and PGC1α between males and females.

RESULTS

OA chondrocytes from male donors showed elevated ribonucleic acid (RNA) and protein levels of SOX9, elevated COL2A1 protein synthesis, higher glucose consumption, and higher usage of glycolysis compared to females. OA chondrocytes from females had higher PGC1α protein levels, higher fat consumption, and higher oxidative energy metabolism than males. Knockdown of SOX9 reduced expression of COL2A1 to a greater extent in male OA chondrocytes than females whereas knockdown of PGC1α reduced COL2A1 expression in females but not males. Expression of ACAN and the glycolytic enzyme PGK1 was also reduced in males but not females following SOX9 knockdown.

CONCLUSIONS

OA chondrocyte phenotype and energy metabolism differ between males and females. Our results indicate transcriptional control of COL2A1 differs between the two. Differences in chondrocyte biology between males and females imply the underlying mechanisms involved in OA may also differ, highlighting the need to consider sex and gender when investigating pathogenesis and potential treatments for OA.

Rat model of recalcitrant prosthetic joint infection using biofilm inocula

Prosthetic joint infection (PJI) is a rare but devastating complication of joint arthroplasty. Biofilm formation around the prosthesis confers tolerance to antibiotics so that treatment is challenging. Most animal models of PJI use planktonic bacteria to establish the infection which fails to reproduce the pathology of chronic infection. We aimed to establish a rat model of Staphylococcus aureus PJI in male Sprague-Dawley rats using biofilm inocula and demonstrate its tolerance to frontline antibiotics. Pilot studies indicated that infection could be introduced to the knee joint by a biofilm-coated pin but that handling the prosthetic without disturbing the biofilm was difficult. We, therefore, developed a pin with a slotted end and used a miniature-biofilm reactor to develop mature biofilm in this niche. These biofilm-laden pins consistently produced infection of the bone and joint space. Treatment with high dose cefazolin, 250 mg/kg, starting the day of surgery reduced or cleared pin-adherent bioburden within 7 days, however when escalation from 25 to 250 mg/kg cefazolin treatment was delayed for 48 h, rats were unable to clear the infection. To track infections, we used bioluminescent bacteria, however, the bioluminescent signal did not accurately track the degree of infection in the bone and joint space as the signal did not penetrate the bone. In conclusion, we demonstrate that using a custom prosthetic pin, we can generate biofilm in a specific niche using a novel bioreactor setup and initiate a rat PJI that rapidly develops tolerance to supra-clinical doses of cefazolin.

Better post-operative outcomes at 1-year follow-up are associated with lower levels of pre-operative synovitis and higher levels of IL-6 and VEGFA in unicompartmental knee arthroplasty patients

PURPOSE

Osteoarthritis (OA) is associated with inflammation, and residual inflammation may influence outcomes following knee arthroplasty. This may be more relevant for patients undergoing unicompartmental knee arthroplasty (UKA) due to larger remaining areas of native tissue. This study aimed to: (1) characterise inflammatory profiles for medial UKA patients and (2) investigate whether inflammation markers are associated with post-operative outcomes.

METHODS

This prospective, observational study has national ethics approval. Bloods, synovial fluid, tibial plateaus and synovium were collected from medial UKA patients in between 1 January 2021 and 31 December 2021. Cytokine and chemokine concentrations in serum and synovial fluid (SF) were measured with multiplexed assays. Disease severity of cartilage and synovium was assessed using validated histological scores. Post-operative outcomes were measured with Oxford Knee Score (OKS), Forgotten Joint Score (FJS-12) and pain scores.

RESULTS

The study included 35 patients. SF VEGFA was negatively correlated with pre-operative pain at rest (r - 0.5, p = 0.007), and FJS-12 at six-week (r 0.44, p = 0.02), six-month (r 0.61, p < 0.01) and one-year follow-up (r 0.63, p = 0.03). Serum and SF IL-6 were positively correlated with OKS at early follow-up (serum 6 weeks, r 0.39, p = 0.03; 6 months, r 0.48, p < 0.01; SF 6 weeks, r 0.35, p = 0.04). At six weeks, increased synovitis was negatively correlated with improvements in pain at rest (r - 0.41, p = 0.03) and with mobilisation (r - 0.37, p = 0.047).

CONCLUSION

Lower levels of synovitis and higher levels of IL-6 and VEGFA were associated with better post-operative outcomes after UKA, which could be helpful for identifying UKA patients in clinical practice.

LEVEL OF EVIDENCE

Level IV case series.

Concentration-dependent effects of leptin on osteoarthritis-associated changes in phenotype of human chondrocytes

Metabolic syndrome is a risk factor for osteoarthritis. Elevated leptin levels have been implicated as a potential cause of this association. Previous studies have shown that supra-physiological leptin concentrations can induce osteoarthritis-like changes in chondrocyte phenotype. Here, we tested the effects of leptin in the concentration range found in synovial fluid on chondrocyte phenotype. Chondrocytes isolated from macroscopically normal regions of cartilage within osteoarthritic joints from patients undergoing knee arthroplasty, all with body mass index >30 kg/m2 were treated with 2-40 ng/ml leptin for 24 h. Chondrocyte phenotype marker expression was measured by RT-qPCR and western blot. The role of HES1 in mediating the effects of leptin was determined by gene knockdown using RNAi and over-expression using adenoviral-mediated gene delivery. Treatment of chondrocytes with 20 or 40 ng/ml leptin resulted in decreased SOX9 levels and decreased levels of the SOX9-target genes COL2A1 and ACAN. Levels of HES1 were lower and ADAMTS5 higher in chondrocytes treated with 20 or 40 ng/ml leptin. HES1 knockdown resulted in increased ADAMTS5 expression whereas over-expression of HES1 prevented the leptin-induced increase in ADAMTS5. An increase in MMP13 expression was only evident in chondrocytes treated with 40 ng/ml leptin and was not mediated by HES1 activity. High concentrations of leptin can cause changes in chondrocyte phenotype consistent with those seen in osteoarthritis. Synovial fluid leptin concentrations of this level are typically observed in patients with metabolic syndrome and/or women, suggesting elevated leptin levels may form part of the multifactorial network that leads to osteoarthritis development in these patients.

Combined Growth Factor Hydrogel Enhances Rotator Cuff Enthesis Healing in Rat But Not Sheep Model

We hypothesized that a combined growth factor hydrogel would improve chronic rotator cuff tear healing in a rat and sheep model. Insulin-like growth factor 1, transforming growth factor β1, and parathyroid hormone were combined into a tyraminated poly-vinyl-alcohol (PVA-Tyr) hydrogel and applied directly at the enthesis. In total, 30 Sprague-Dawley rats and 16 Romney ewes underwent unilateral rotator cuff tenotomy and then delayed repairs were performed after 3-4 weeks. The animals were divided into a control group (repair alone) and treatment group. The rotator cuffs were harvested at 12 weeks after surgery for biomechanical and histological analyses of the repair site. In the rat model, the stress at failure and Young's modulus were higher in the treatment group in comparison with the control group (73% improvement, p = 0.010 and 56% improvement, p = 0.028, respectively). Histologically, the repaired entheses in the treatment group demonstrated improved healing with higher semi-quantitative scores (10.1 vs. 6.55 of 15, p = 0.032). In the large animal model, there was no observable treatment effect. This PVA-Tyr bound growth factor system holds promise for improving rotator cuff healing. However, our approach was not scalable from a small to a large animal model. Further tailoring of this growth factor delivery system is still required. Level of Evidence: Basic Science Study; Biomechanics and Histology; Animal Model Impact Statement Previous studies using single-growth factor treatment to improve enthesis healing after rotator cuff repair have reported promising, but inconsistent results. A novel approach is to combine multiple growth factors using controlled-release hydrogels that mimic the normal healing process. In this study, we report that a combined growth factor hydrogel can improve the histological quality and strength of rotator cuff repair in a rat chronic tear model. This novel hydrogel growth factor treatment has the potential to be used in human clinical applications to improve healing after rotator cuff repair.

REST, RCOR1 and RCOR2 expression is reduced in osteoarthritic chondrocytes and contributes to increasing MMP13 and ADAMTS5 expression through upregulating HES1

Expression of key transcriptional regulators is altered in chondrocytes in osteoarthritis (OA). This contributes to an increase in production of cartilage-catabolizing enzymes such as MMP13 and ADAMTS5. RCOR1 and RCOR2, binding partners for the transcriptional repressor REST, have previously been found to be downregulated in OA chondrocytes although their function in chondrocytes is unclear. HES1 is a known REST/RCOR1 target gene and HES1 has been shown to promote MMP13 and ADAMTS5 expression in murine OA chondrocytes. The purpose of this study was to determine whether reduced REST/RCOR levels leads to increased HES1 expression in human OA chondrocytes and whether HES1 also promotes ADAMTS5 and MMP13 expression in these cells. Chondrocytes were isolated from osteoarthritic and adjacent macroscopically normal cartilage obtained from patients undergoing total knee arthroplasty. RNA and protein levels of REST, RCOR1 and RCOR2 were lower, but levels of HES1 higher, in chondrocytes isolated from osteoarthritic compared to macroscopically normal cartilage. Over-expression of either REST, RCOR1 or RCOR2 resulted in reduced HES1 levels in OA chondrocytes whereas knockdown of REST, RCOR1 or RCOR2 led to increased HES1 expression in chondrocytes from macroscopically normal cartilage. In OA chondrocytes, ADAMTS5 and MMP13 expression were reduced following HES1 knockdown, but further enhanced following HES1 over-expression. Levels of phosphorylated CaMKII were higher in chondrocytes from OA cartilage consistent with previous findings that HES1 only promotes gene transcription in the presence of active CaMKII. These findings identify the REST/RCOR/HES1 pathway as a contributing factor leading to increased ADAMTS5 and MMP13 expression in OA chondrocytes.

Differential Effects of Hypoxia versus Hyperoxia or Physoxia on Phenotype and Energy Metabolism in Human Chondrocytes from Osteoarthritic Compared to Macroscopically Normal Cartilage

Chondrocyte phenotype and energy metabolism are altered in osteoarthritis (OA). However, most studies characterising the change in human chondrocyte behaviour in OA have been conducted in supraphysiological oxygen concentrations. The purpose of this study was to compare phenotype and energy metabolism in chondrocytes from macroscopically normal (MN) and OA cartilage maintained in 18.9% (standard tissue culture), 6% (equivalent to superficial zone of cartilage in vivo) or 1% oxygen (equivalent to deep zone of cartilage in vivo). MMP13 production was higher in chondrocytes from OA compared to MN cartilage in hyperoxia and physoxia but not hypoxia. Hypoxia promoted SOX9, COL2A1 and ACAN protein expression in chondrocytes from MN but not OA cartilage. OA chondrocytes used higher levels of glycolysis regardless of oxygen availability. These results show that differences in phenotype and energy metabolism between chondrocytes from OA and MN cartilage differ depending on oxygen availability. OA chondrocytes show elevated synthesis of cartilage-catabolising enzymes and chondrocytes from MN cartilage show reduced cartilage anabolism in oxygenated conditions. This is relevant as a recent study has shown that oxygen levels are elevated in OA cartilage in vivo. Our findings may indicate that this elevated cartilage oxygenation may promote cartilage loss in OA.

Robotic-arm assisted unicompartmental knee arthroplasty system has a learning curve of 11 cases and increased operating time

PURPOSE

UKA has higher revision risk, particularly for lower volume surgeons. While robotic-arm assisted systems allow for increased accuracy, introduction of new systems has been associated with learning curves. The aim of this study was to determine the learning curve of a UKA robotic-arm assisted system. The hypothesis was that this may affect operative times, patient outcomes, limb alignment, and component placement.

METHODS

Between 2017 and 2021, five surgeons performed 152 consecutive robotic-arm assisted primary medial UKA, and measurements of interest were recorded. Patient outcomes were measured with Oxford Knee Score, EuroQol-5D, and Forgotten Joint Score at 6 weeks, 1 year, and 2 years. Surgeons were grouped into 'low' and 'high' usage groups based on total UKA (manual and robotic) performed per year.

RESULTS

A learning curve of 11 cases was found with operative time (p < 0.01), femoral rotation (p = 0.02), and insert sizing (p = 0.03), which highlighted areas that require care during the learning phase. Despite decreased 6-week EQ-5D-5L VAS in the proficiency group (77 cf. 85, p < 0.01), no difference was found with implant survival (98.2%) between phases (p = 0.15), or between 'high' and 'low' usage surgeons (p = 0.23) at 36 months. This suggested that the learning curve did not lead to early adverse effects in this patient cohort.

CONCLUSION

Introduction of a UKA robotic-arm assisted system showed learning curves for operative times and insert sizing but not for implant survival at early follow-up. The short learning curve regardless of UKA usage indicated that robotic-arm assisted UKA may be particularly useful for low-usage surgeons.

LEVEL OF EVIDENCE

Level III, Retrospective cohort study.

Clinical and Functional Outcomes of the Exeter V40 Short Stem in Primary and Revision Arthroplasty: Does the Indication Affect Outcomes in the Short Term?

Purpose

A variety of short Exeter stems designed specifically for use in performance of total hip arthroplasty (THA) in primary and revision settings have recently been introduced. Some have been used 'off label' for hip reconstruction. The aim of this study is to report clinical and radiological results from the Exeter V40 125 mm stem in performance of primary THA and revision THA.

Materials and Methods

This study had a retrospective design. Insertion of 58 (24 primary, 34 revision) Exeter V40 125 mm stems was performed between 2015 and 2017. The minimum follow-up period was two years. Assessment of the Oxford hip score (OHS), EuroQol-5 Dimension (EQ-5D), and radiological follow-up was performed at one and two years.

Results

In the primary group, the preoperative, mean OHS was 13.29. The mean OHS was 32.86 and 23.39 at one-year and two-year post-surgery, respectively. The mean EQ-5D-3L scores were at 0.14, 0.59, and 0.35, preoperatively, at one-year follow-up and two-year follow-up, respectively. In the revision group, the mean preoperative OHS was 19.41. The mean OHS was 30.55 and 26.05 at one-year and two-year post-surgery, respectively. The mean EQ-5D-3L scores were 0.33, 0.61, and 0.48 preoperatively, at one-year follow-up and two-year follow-up, respectively. No progressive or new radiolucent lines were observed around any stem at the time of the final follow-up in all patients in both groups.

Conclusion

Encouraging results regarding use of Exeter V40 125 mm stems have been reported up to two years following surgery in primary and revision THA settings.

Similar Survivorship but Different Revision Reasons for Uncemented Mobile-Bearing and Cemented Fixed-Bearing Medial UKA: A Long-Term Population-Based Cohort Study of 2,015 Patients

BACKGROUND

Long-term survivorship and accurate characterization of revision reasons in unicompartmental knee arthroplasty (UKA) are limited by a lack of long-term data and standardized definitions of revision. The aim of this study was to identify survivorship, risk factors, and reasons for revision in a large cohort of medial UKAs with long-term follow-up (up to 20 years).

METHODS

Patient, implant, and revision details for 2,015 primary medial UKAs (mean follow-up, 8 years) were recorded following systematic clinical and radiographic review. Survivorship and risk of revision were analyzed using Cox proportional hazards. Reasons for revision were analyzed using competing-risk analysis.

RESULTS

Implant survivorship at 15 years was 92% for cemented fixed-bearing (cemFB), 91% for uncemented mobile-bearing (uncemMB), and 80% for cemented mobile-bearing (cemMB) UKAs (p = 0.02). When compared with cemFB, the risk of revision was higher for cemMB implants (hazard ratio [HR] = 1.9, 95% confidence interval [CI] = 1.1 to 3.2; p = 0.03). At 15 years, cemented implants had a higher cumulative frequency of revision due to aseptic loosening (3% to 4%, versus 0.4% for uncemented; p < 0.01), cemMB implants had a higher cumulative frequency of revision due to osteoarthritis progression (9% versus 2% to 3% for cemFB/uncemMB; p < 0.05), and uncemMB implants had a higher cumulative frequency of revision due to bearing dislocation (4% versus 2% for cemMB; p = 0.02). Compared with the oldest patients (≥70 years), younger patients had a higher risk of revision (<60 years: HR = 1.9, 95% CI = 1.2 to 3.0; 60 to 69 years: HR = 1.6, 95% CI = 1.0 to 2.4; p < 0.05 for both). At 15 years, there was a higher cumulative frequency of revision for aseptic loosening in these younger groups (3.2% and 3.5% versus 2.7% for ≥70 years; p < 0.05).

CONCLUSIONS

Implant design and patient age were risk factors for revision of medial UKA. The findings from this study suggest that surgeons should consider using cemFB or uncemMB designs because of their superior long-term implant survivorship compared with cemMB designs. Additionally, for younger patients (<70 years), uncemMB designs had a lower risk of aseptic loosening than cemFB designs at the expense of a risk of bearing dislocation.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Ethnicity, sex, and socioeconomic disparities in the treatment of traumatic rotator cuff injuries in Aotearoa/New Zealand

HYPOTHESIS AND BACKGROUND

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

METHODS

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.

RESULTS

During the 9-year study period, there were 351,554 claims accepted for traumatic rotator cuff injury, which totaled more than NZ$960 million. 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 socioeconomic deprivation.

DISCUSSION AND CONCLUSION

This large nationwide 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 sociodemographic disparities that need to be addressed in order to achieve equity in health outcomes.

Introduction of ROSA robotic-arm system for total knee arthroplasty is associated with a minimal learning curve for operative time

Purpose

The introduction of robotics for total knee arthroplasty (TKA) into the operating theatre is often associated with a learning curve and is potentially associated with additional complications. The purpose of this study was to determine the learning curve of robotic-assisted (RA) TKA within a multi-surgeon team.

Methods

This prospective cohort study included 83 consecutive conventional jig-based TKAs compared with 53 RA TKAs using the Robotic Surgical Assistant (ROSA) system (Zimmer Biomet, Warsaw, Indiana, USA) for knee osteoarthritis performed by three high-volume (> 100 TKA per year) orthopaedic surgeons. Baseline characteristics including age, BMI, sex and pre-operative Kellgren-Lawrence graded and Hip-Knee-Ankle Axis were well-matched between the conventional and RA TKA groups. Cumulative summation (CUSUM) analysis was used to assess learning curves for operative times for each surgeon. Peri-operative and delayed complications (infection, periprosthetic fracture, thromboembolism, and compromised wound healing) and revisions were reviewed.

Results

The CUSUM analysis for operative time demonstrated an inflexion point after 5, 6 and 15 cases for each of the three surgeons, or 8.7 cases on average. There were no significant differences (p = 0.53) in operative times between the RA TKA learning (before inflexion point) and proficiency (after inflexion point) phases. Similarly, the operative times of the RA TKA group did not differ significantly (p = 0.92) from the conventional TKA group. There was no discernible learning curve for the accuracy of component planning using the RA TKA system. The average length of post-operative follow-up was 21.3 ± 9.0 months. There was one revision for instability in the conventional TKA group and none in the RA TKA group. There were no significant difference (p > 0.99) in post-operative complication rates between the conventional TKA and RA TKA groups.

Conclusions

The introduction of the RA TKA system was associated with a learning curve for operative time of 8.7 cases. Operative times between the RA TKA and conventional TKA group were similar. The short learning curve implies this RA TKA system can be adopted relatively quickly into a surgical team with minimal risks to patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-022-00524-5.

Five-year results after total knee arthroplasty in lymphoedema and lipoedema: encouraging functional and clinical outcomes and low rates of infection

BACKGROUND

The aim of this study was to define outcomes after total knee arthroplasty (TKA) in lymphoedema and lipoedema patients managed by a multidisciplinary team and daily compression bandaging.

METHODS

A retrospective study was performed in a single centre. Between 2007 and 2018, 36 TKA procedures were performed on 28 consecutive patients with a diagnosis of lymphoedema and lipoedema. Oxford Knee Scores (OKS), EuroQol-5D (EQ-5D) scores, satisfaction scores, radiographs, and complications were obtained at the final follow-up. Patients were admitted to the hospital up to two weeks prior to surgery and remained on the ward for daily compression bandaging by the specialist lymphoedema team.

RESULTS

Over the study period, 36 TKAs were performed on 28 patients (5 males, 23 females) with a mean age of 71 years (range 54-90). Of these, 30 TKAs were in patients with lymphoedema, five with lipoedema, and one with a dual diagnosis. Overall, 28 TKAs (21 patients) were available at the final follow-up with a mean follow-up time of 61 months (range 9-138). The mean BMI was 38.5 kg/m². The mean pre-operative and post-operative Oxford Knee Score increased from 18 (range 2-38) to 29 (range 10-54); p < 0.001. EQ-5D score increased from 0.48 (range 0.15-0.80) to 0.74 (0.34-1.00) (p < 0.001). Mean post-operative satisfaction was 7.6/10 (range 2-10), with 89.3% TKAs satisfied. Complications were one (4%, 1/28) deep vein thrombosis, one superficial wound infection, one prosthetic joint infection, one stiff knee requiring manipulation, and one intra-operative femoral fracture.

CONCLUSIONS

Lymphoedema and lipoedema should not be seen as barriers to TKA if adopting a multidisciplinary approach.

The effect of COVID-19 on orthopaedics in Aotearoa New Zealand-a survey of orthopaedic surgeons and training registrars

AIM

This study aimed to assess the impact of COVID-19 on orthopaedic practice in New Zealand, with a focus on training and mental health.

METHODS

An online survey was sent to the 385 consultant orthopaedic surgeons and registrars in New Zealand registered with the New Zealand Orthopaedic Association (NZOA). The survey consisted of 27 questions relating to demographics, the effects of COVID-19 on orthopaedic departments, on training, on mental health and the utilisation of telehealth and online teaching.

RESULTS

In total, 189 of 385 NZOA members (49%) completed the survey. Of the 51 orthopaedic registrars surveyed, 55% felt that their training had been moderately affected, while 17% felt it had been significantly affected. Of those surveyed, 65% felt the pandemic had at least a mild effect on their mental health. Seven percent of registrars described a significant impact on their mental health compared to 2% of consultants (p=0.029). Overall, 46.5% felt they were more burnt out because of the pandemic, which was significantly higher in registrars compared to consultants (51% vs 44%, respectively; p=0.029).

CONCLUSIONS

Despite the comparatively low number of COVID-19 cases, hospitalisations and deaths, the effects for orthopaedic surgeons and training registrars have been significant.

Tibial metaphyseal cones combined with short stems perform as well as long stems in revision total knee arthroplasty

Backgrounds

There is uncertainty around optimal tibial stem length in revision total knee arthroplasty (rTKA) utilizing a tibial trabecular metal (TM) cone. The purpose of this study was to compare: (1) functional outcomes, (2) radiographic outcomes and (3) implant survivorship in rTKA utilizing TM cones combined with either short stems (SS) or long stems (LS) at minimum 2 years follow‐up.

Methods

In this retrospective, multi‐centre study, patients undergoing rTKA utilizing a TM cone between 2008 and 2019 were included. Patients were divided into: SS group (no diaphyseal engagement), and LS group (diaphyseal engagement). All relevant clinical charts and post‐operative radiographs were examined. Oxford Knee Score (OKS) and EuroQol‐5D (EQ‐5D‐5L) data were collected at most recent follow‐up.

Results

In total, 44 patients were included: 18 in the SS group and 26 in the LS group. The mean time of follow‐up was 4.0 years. Failure free survival was 94.4% for the SS group and 92.3% for the LS group. All failures were for prosthetic joint infections managed with debridement, antibiotics, and implant retention. At most recent follow‐up, 3 patients demonstrated radiographic signs of lucency (1 SS 2 LS, P = 1) and the mean OKS were 37 ± 4 and 36 ± 6 (P = 0.73) in the SS and LS groups, respectively.

Conclusion

Tibial SS combined with TM cones performed as well as LS in rTKA at minimum 2 years follow‐up. A tibial SS in combination with a TM cone is a reliable technique to achieve stable and durable fixation in rTKA.

Poor compliance documenting informed consent in trauma patients with distal radius fractures compared to elective total knee arthroplasty

Background

The purpose of this study was (1) to evaluate the adequacy of informed consent documentation in the trauma setting for distal radius fracture surgery compared with the elective setting for total knee arthroplasty (TKA) at a large public hospital and (2) to explore the relevant guidelines in New Zealand relating to consent documentation.

Methods

Consecutive adult patients (≥16 years) undergoing operations for distal radius fractures and elective TKA over a 12‐month period in a single‐centre were retrospectively identified. All medical records were reviewed for the risks and complications recorded. The consent form was analysed using the Flesch Reading Ease Score (FRES) and the Simple Measure of Gobbledygook (SMOG) index readability scores.

Results

A total of 133 patients undergoing 134 operations for 135 distal radius fractures and 239 patients undergoing 247 TKA were included. Specific risks of surgery were recorded significantly less frequently for distal radius fractures than TKA (43.3% versus 78.5%, P < 0.001). Significantly fewer risks were recorded in the trauma setting compared to the elective (2.35 ± 2.98 versus 4.95 ± 3.33, P < 0.001). The readability of the consent form was 40.5 using the FRES and 10.9 using the SMOG index, indicating a university undergraduate level of reading.

Conclusions

This study has shown poor compliance in documenting risks of surgery during the informed consent process in an acute trauma setting compared to elective arthroplasty. Institutions must prioritize improving documentation of informed consent for orthopaedic trauma patients to ensure a patient‐centred approach to healthcare.

Cytotoxicity of tranexamic acid to tendon and bone in vitro: Is there a safe dosage?

Introduction

Tranexamic acid (TXA) has been shown to be effective at reducing peri-operative blood loss and haemarthrosis in arthroplasty and arthroscopic soft tissue reconstructions. Intra-articular application, as an injection or peri-articular wash, is becoming increasingly common. Recent studies have shown TXA has the potential to be cytotoxic to cartilage, but its effects on human tendon and bone remain poorly understood. The aim of this study was to investigate whether TXA has any detrimental effects on tendon-derived cells and osteoblast-like cells and determine whether there is a safe dosage for clinical application.

Materials and methods

Primary tendon-derived cells and osteoblast-like cells were harvested from hamstring tendons and trabecular bone explants, respectively, and analysed in vitro with a range of TXA concentrations (0 to 100 mg/ml) at time points: 3 and 24 h. The in vitro toxic effect of TXA was investigated using viability assays (alamarBlue), functional assays (collagen deposition), fluorescent microscopy and live/apoptosis/necrosis staining for cell death mechanisms in 2D monolayer and 3D collagen gel cell culture.

Results

There was a significant (P < 0.05) decrease in tendon-derived cell and osteoblast-like cell numbers following treatment with TXA ≥ 50 mg/ml after 3 h and ≥ 20 mg/ml after 24 h. In tendon-derived cells, increasing concentrations > 35 mg/ml resulted in significantly (P < 0.05) reduced collagen deposition. Fluorescence imaging confirmed atypical cellular morphologies with increasing TXA concentrations and reduced cell numbers. The mechanism of cell death was demonstrated to be occurring through apoptosis.

Conclusions

Topical TXA treatment demonstrated dose- and time-dependent cytotoxicity to tendon-derived cells and osteoblast-like cells with concentrations 20 mg/ml and above in isolated 2D and 3D in vitro culture. On the basis of these findings, concentrations of less than 20 mg/ml are expected to be safe. Orthopaedic surgeons should show caution when considering topical TXA treatments, particularly in soft tissue and un-cemented arthroplasty procedures.

A high-fat diet has negative effects on tendon resident cells in an in vivo rat model

BACKGROUND

Tendinopathy is a major complication of diet-induced obesity. However, the effects of a high-fat diet (HFD) on tendon have not been well characterised. We aimed to determine: [1] the impact of a HFD on tendon properties and gene expression; and [2] whether dietary transition to a control diet (CD) could restore normal tendon health.

METHODS

Sprague-Dawley rats were randomised into three groups from weaning and fed either a: CD, HFD or HFD for 12 weeks and then CD thereafter (HF-CD). Biomechanical, histological and structural evaluation of the Achilles tendon was performed at 17 and 27 weeks of age. Tail tenocytes were isolated with growth rate and collagen production determined. Tenocytes and activated THP-1 cells were exposed to conditioned media (CM) of visceral adipose tissue explants, and gene expression was analysed.

RESULTS

There were no differences in the biomechanical, histological or structural tendon properties between groups. However, tenocyte growth and collagen production were increased in the HFD group at 27 weeks. There was lower SOX-9 expression in the HFD and HF-CD groups at 17 weeks and higher expression of collagen-Iα1 and matrix metalloproteinase-13 in the HFD group at 27 weeks. THP-1 cells exposed to adipose tissue CM from animals fed a HFD or HF-CD had lower expression of Il-10 and higher expression of Il-1β.

CONCLUSIONS

In this rodent model, a HFD negatively altered tendon cell characteristics. Dietary intervention restored some gene expression changes; however, adipose tissue secretions from the HF-CD group promoted an increased inflammatory state in macrophages. These changes may predispose tendon to injury and adverse events later in life.

Novel Growth Factor Combination for Improving Rotator Cuff Repair: A Rat In Vivo Study

BACKGROUND

The lack of healing at the repaired tendon-bone interface is an important cause of failure after rotator cuff repair. While augmentation with growth factors (GFs) has demonstrated promise, the ideal combination must target all 3 tissue types at the tendon-bone interface.

HYPOTHESIS

The GF combination of transforming growth factor beta 1, Insulin-like growth factor 1, and parathyroid hormone will promote tenocyte proliferation and differentiation and improve the biomechanical and histological quality of the repaired tendon-bone interface.

STUDY DESIGN

Controlled laboratory study.

METHODS

In vitro, human tenocytes were cultured in the presence of the GF combination for 72 hours, and cell growth assays and the expression of genes specific to tendon, cartilage, and bone were analyzed. In vivo, adult rats (N = 46) underwent detachment and repair of the left supraspinatus tendon. A PVA-tyramine gel was used to deliver the GF combination to the tendon-bone interface. Histological, biomechanical, and RNA microarray analysis was performed at 6 and 12 weeks after surgery. Immunohistochemistry for type II and X collagen was performed at 12 weeks.

RESULTS

When treated with the GF combination in vitro, human tenocytes proliferated 1.5 times more than control (P = .04). The expression of scleraxis increased 65-fold (P = .013). The expression of Sox-9 (P = .011), type I collagen (P = .021), fibromodulin (P = .0075), and biglycan (P = .010) was also significantly increased, while the expression of PPARγ was decreased (P = .007). At 6 and 12 weeks postoperatively, the quality of healing on histology was significantly higher in the GF group, with the formation of a more mature tendon-bone interface, as confirmed by immunohistochemistry for type II and X collagen. The GF group achieved a load at failure and Young modulus >1.5 times higher at both time points. Microarrays at 6 weeks demonstrated upregulation of genes involved in leukocyte aggregation (S100A8, S100A9) and tissue mineralization (Bglap, serglycin, Fam20c).

CONCLUSION

The GF combination promoted protendon and cartilage responses in human tenocytes in vitro; it also improved the histological appearance and mechanical properties of the repair in vivo. Microarrays of the tendon-bone interface identified inflammatory and mineralization pathways affected by the GF combination, providing novel therapeutic targets for further research.

CLINICAL RELEVANCE

The use of this GF combination is translatable to patients and may improve healing after rotator cuff repair.

Changes in Physiological Tendon Substrate Stiffness Have Moderate Effects on Tendon-Derived Cell Growth and Immune Cell Activation

Tendinopathy is characterised by pathological changes in tendon matrix composition, architecture, and stiffness, alterations in tendon resident cell characteristics, and fibrosis, with inflammation also emerging as an important factor in tendinopathy progression. The sequence of pathological changes in tendinopathy and the cellular effects of the deteriorating matrix are largely unknown. This study investigated the effects of substrate stiffness on tendon-derived cells (TDCs) and THP-1 macrophages using PDMS substrates representing physiological tendon stiffness (1.88 MPa), a stiff gel (3.17 MPa) and a soft gel (0.61 MPa). Human TDCs were cultured on the different gel substrates and on tissue culture plastic. Cell growth was determined by alamarBlue™ assay, cell morphology was analysed in f-actin labelled cells, and phenotypic markers were analysed by real-time PCR. We found that in comparison to TDCs growing on gels with physiological stiffness, cell growth increased on soft gels at 48 h (23%, p = 0.003). Cell morphology was similar on all three gels. SCX expression was slightly reduced on the soft gels (1.4-fold lower, p = 0.026) and COL1A1 expression increased on the stiff gels (2.2-fold, p = 0.041). Culturing THP-1 macrophages on soft gels induced increased expression of IL1B (2-fold, p = 0.018), and IL8 expression was inhibited on the stiffer gels (1.9-fold, p = 0.012). We also found that culturing TDCs on plastic increased cell growth, altered cell morphology, and inhibited the expression of SCX, SOX9, MMP3, and COL3. We conclude that TDCs and macrophages respond to changes in matrix stiffness. The magnitude of responses measured in TDCs were minor on the range of substrate stiffness tested by the gels. Changes in THP-1 macrophages suggested a more inflammatory phenotype on substrates with non-physiological stiffness. Although cell response to subtle variations in matrix stiffness was moderate, it is possible that these alterations may contribute to the onset and progression of tendinopathy.

Obesity Impairs Enthesis Healing After Rotator Cuff Repair in a Rat Model

BACKGROUND

Being overweight or obese is associated with poor outcomes and an increased risk of failure after rotator cuff (RC) surgery. However, the effect of obesity on enthesis healing has not been well characterized.

HYPOTHESES

Diet-induced obesity (DIO) would result in inferior enthesis healing in a rat model of RC repair, and a dietary intervention in the perioperative period would improve enthesis healing.

STUDY DESIGN

Controlled laboratory study.

METHODS

Male Sprague-Dawley rats were divided into 3 weight-matched groups (n = 26 per group): control diet (CD), high-fat diet (HFD), or HFD until surgery and then CD thereafter (HF-CD). After 12 weeks, the left supraspinatus tendon was detached, followed by immediate repair. Animals were sacrificed, and RCs were harvested at 2 and 12 weeks after surgery for biomechanical and histological evaluations. Metabolic end points were assessed using dual-energy X-ray absorptiometry and plasma analyses.

RESULTS

DIO was established in the HFD and HF-CD groups before surgery and subsequently reversed in the HF-CD group after surgery. At 12 weeks after surgery, the body fat percentage (P = .0021) and plasma leptin concentration (P = .0025) were higher in the HFD group compared with the CD group. 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 6.20 (P = .0078), 4.98 (P = .0003), and 8.68 of 15, respectively. The repaired entheses in the HF-CD group had a significantly lower load to failure (P = .0278) 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 = .0960). There were no differences in the biomechanical and histological results between the groups at 2 weeks after surgery. Body mass at the time of surgery, plasma leptin concentration, and body fat percentage were negatively correlated with histology scores and plasma leptin concentration was correlated with load to failure at 12 weeks after surgery.

CONCLUSION

DIO impaired enthesis healing in this rat RC repair model, with inferior biomechanical and histological outcomes. Restoring a normal weight with dietary changes after surgery did not improve healing outcomes.

CLINICAL RELEVANCE

Obesity is a potentially modifiable factor that impairs RC healing and increases the risk of failure after surgery. Exploring interventions that improve the metabolic state of obese patients and counseling patients appropriately about their modest expectations after repair should be considered.

IL-1β induces changes in expression of core circadian clock components PER2 and BMAL1 in primary human chondrocytes through the NMDA receptor/CREB and NF-κB signalling pathways

The circadian clock is a specialised cell signalling circuit present in almost all cells. It controls the timing of key cell activities such as proliferation and differentiation. In osteoarthritis, expression of two components of the circadian clock, BMAL1 and PER2 is altered in chondrocytes and this change has been causally linked with the increase in proliferation and altered chondrocyte differentiation in disease. IL-1β, an inflammatory cytokine abundant in OA joints, has previously been shown to induce changes in BMAL1 and PER2 expression in chondrocytes. The purpose of this study is to identify the mechanism involved. We found IL-1β treatment of primary human chondrocytes led to activation of NMDA receptors as evidenced by an increase in phosphorylation of GluN1 and an increase in intracellular calcium which was blocked by the NMDAR antagonist MK801. Levels of phosphorylated CREB were also elevated in IL-1β treated cells and this effect was blocked by co-treatment of cells with IL-1β and the NMDAR antagonist MK-801. Knockdown of CREB or inhibition of CREB activity prevented the IL-1β induced increase in PER2 expression in chondrocytes but had no effect on BMAL1. Phosphorylated p65 levels were elevated in IL-1β treated chondrocytes indicating increased NF-κB activation. Inhibition of NF-κB activity prevented the IL-1β induced reduction in BMAL1 expression and partially mitigated the IL-1β induced increase in PER2 expression in chondrocytes. These data indicate that the NMDAR/CREB and NF-κB signalling pathways regulate the core circadian clock components PER2 and BMAL1 in chondrocytes. Given that changes in expression of these clock components have been observed in a wide range of diseases, these findings may be broadly relevant for understanding the mechanism leading to circadian clock changes in pathology.

The Impact of Maternal High-Fat Diet on Bone Microarchitecture in Offspring

The incidence of obesity in women of reproductive age has significantly increased over the past 100 years. There is a well-established connection between maternal obesity during pregnancy and an increased risk of developing non-communicable cardiometabolic diseases in her offspring. This mini-review focuses on evidence examining the effect of maternal high-fat diet (HFD) on skeletal development and bone health in later life in offspring. The majority of rodent studies indicate that maternal HFD generally negatively affects both embryonic bone development and bone volume in adult animals. Details surrounding the mechanisms of action that drive changes in the skeleton in offspring remain unclear, although numerous studies suggest that some effects are sex-specific. Human studies in this area are limited but also suggest that HFD during pregnancy may impair bone formation and increase fracture risk during childhood. Given the consequences of low bone mass and deranged bone microarchitecture for offspring, advances in our understanding of the developmental origins of bone health is critical in the battle against osteoporosis.

A Maternal High Fat Diet Leads to Sex-Specific Programming of Mechanical Properties in Supraspinatus Tendons of Adult Rat Offspring

Background: Over half of women of reproductive age are now overweight or obese. The impact of maternal high-fat diet (HFD) is emerging as an important factor in the development and health of musculoskeletal tissues in offspring, however there is a paucity of evidence examining its effects on tendon. Alterations in the early life environment during critical periods of tendon growth therefore have the potential to influence tendon health that cross the lifespan. We hypothesised that a maternal HFD would alter biomechanical, morphological and gene expression profiles of adult offspring rotator cuff tendon. Materials and Methods: Female Sprague-Dawley rats were randomly assigned to either: control diet (CD; 10% kcal or 43 mg/g from fat) or HFD (45% kcal or 235 mg/g from fat) 14 days prior to mating and throughout pregnancy and lactation. Eight female and male offspring from each maternal diet group were weaned onto a standard chow diet and then culled at postnatal day 100 for tissue collection. Supraspinatus tendons were used for mechanical testing and histological assessment (cellularity, fibre organisation, nuclei shape) and tail tendons were collected for gene expression analysis. Results: A maternal HFD increased the elasticity (Young's Modulus) in the supraspinatus tendon of male offspring. Female offspring tendon biomechanical properties were not affected by maternal HFD. Gene expression of SCX and COL1A1 were reduced in male and female offspring of maternal HFD, respectively. Despite this, tendon histological organisation were similar between maternal diet groups in both sexes. Conclusion: An obesogenic diet during pregnancy increased tendon elasticity in male, but not female, offspring. This is the first study to demonstrate that maternal diet can modulate the biomechanical properties of offspring tendon. A maternal HFD may be an important factor in regulating adult offspring tendon homeostasis that may predispose offspring to developing tendinopathies and adverse tendon outcomes in later life.

Remote Patient Monitoring with Wearable Sensors Following Knee Arthroplasty

(Background) Inertial Measurement Units (IMUs) provide a low-cost, portable solution to obtain functional measures similar to those captured with three-dimensional gait analysis, including spatiotemporal gait characteristics. The primary aim of this study was to determine the feasibility of a remote patient monitoring (RPM) workflow using ankle-worn IMUs measuring impact load, limb impact load asymmetry and knee range of motion in combination with patient-reported outcome measures. (Methods) A pilot cohort of 14 patients undergoing primary knee arthroplasty for osteoarthritis was prospectively enrolled. RPM in the community was performed weekly from 2 up to 6 weeks post-operatively using wearable IMUs. The following data were collected using IMUs: mobility (Bone Stimulus and cumulative impact load), impact load asymmetry and maximum knee flexion angle. In addition, scores from the Oxford Knee Score (OKS), EuroQol Five-dimension (EQ-5D) with EuroQol visual analogue scale (EQ-VAS) and 6 Minute Walk Test were collected. (Results) On average, the Bone Stimulus and cumulative impact load improved 52% (p = 0.002) and 371% (p = 0.035), compared to Post-Op Week 2. The impact load asymmetry value trended (p = 0.372) towards equal impact loading between the operative and non-operative limb. The mean maximum flexion angle achieved was 99.25° at Post-Operative Week 6, but this was not significantly different from pre-operative measurements (p = 0.1563). There were significant improvements in the mean EQ-5D (0.20; p = 0.047) and OKS (10.86; p < 0.001) scores both by 6 weeks after surgery, compared to pre-operative scores. (Conclusions) This pilot study demonstrates the feasibility of a reliable and low-maintenance workflow system to remotely monitor post-operative progress in knee arthroplasty patients. Preliminary data indicate IMU outputs relating to mobility, impact load asymmetry and range of motion can be obtained using commercially available IMU sensors. Further studies are required to directly correlate the IMU sensor outputs with patient outcomes to establish clinical significance.

Toxicity of tranexamic acid (TXA) to intra-articular tissue in orthopaedic surgery: a scoping review

PURPOSE

Intra-articular administration of tranexamic acid (TXA) in orthopaedic arthroplasty and arthroscopic procedures has become increasingly common over the past decade. However, several recent reports have shown that TXA has the potential to be cytotoxic to cartilage, tendon and synovium. Our aim was to review the literature for evidence of toxic effects from TXA exposure to intra-articular tissue.

METHODS

A scoping review methodology was used to search for studies assessing the toxic effects of TXA exposure to intra-articular tissues. MEDLINE, EMBASE, SCOPUS and The Cochrane Library were searched. Relevant information was extracted and synthesis of the retrieved data followed a basic content analytical approach.

RESULTS

A total of 15 laboratory studies were retrieved. No clinical studies reporting a toxic effect of TXA on intra-articular tissue were identified in our search. Studies were analysed according to species of origin, tissue of origin and study setting (in vitro, ex vivo, or in vivo). There was increasing cytotoxicity to chondrocytes, tenocytes, synoviocytes and periosteum-derived cells with TXA concentrations beyond 20 mg/ml. Monolayer cell cultures appear more susceptible to TXA exposure, than three-dimensional and explant culture models. In vivo studies have not demonstrated a major toxic effect.

CONCLUSIONS

Current evidence suggests a dose-dependent toxic effect on cartilage, tendon, and synovial tissue. Concentrations of 20 mg/ml or less are expected to be safe. There is a significant body of evidence to suggest the need for caution with intraarticular administration of TXA. There is a need for further human clinical trials in order to clarify the long-term safety of TXA topical application.

Infection prevention measures for orthopaedic departments during the COVID-2019 pandemic: a review of current evidence

AIM

The coronavirus disease 2019 (COVID-19) pandemic presents significant challenges to healthcare systems globally. Orthopaedic surgeons are at risk of contracting COVID-19 due to their close contact with patients in both outpatient and theatre environments. The aim of this review was to perform a literature review, including articles of other coronaviruses, to formulate guidelines for orthopaedic healthcare staff.

METHODS

A search of Medline, EMBASE, the Cochrane Library, World Health Organization (WHO), and Centers for Disease Control and Prevention (CDC) databases was performed encompassing a variety of terms including 'coronavirus', 'covid-19', 'orthopaedic', 'personal protective environment' and 'PPE'. Online database searches identified 354 articles. Articles were included if they studied any of the other coronaviruses or if the basic science could potentially applied to COVID-19 (i.e. use of an inactivated virus with a similar diameter to COVID-19). Two reviewers independently identified and screened articles based on the titles and abstracts. 274 were subsequently excluded, with 80 full-text articles retrieved and assessed for eligibility. Of these, 66 were excluded as they compared personal protection equipment to no personal protection equipment or referred to prevention measures in the context of bacterial infections.

RESULTS

There is a paucity of high quality evidence surrounding COVID-19. This review collates evidence from previous coronavirus outbreaks to put forward recommendations for orthopaedic surgeons during the COVID-19 pandemic. The key findings have been summarized and interpreted for application to the orthopaedic operative setting.

CONCLUSION

For COVID-19 positive patients, minimum suggested PPE includes N95 respirator, goggles, face shield, gown, double gloves, and surgical balaclava.Space suits not advised.Be trained in the correct technique of donning and doffing PPE.Use negative pressure theatres if available.Minimize aerosolization and its effects (smoke evacuation and no pulse lavage).Minimize further unnecessary patient-staff contact (dissolvable sutures, clear dressings, split casts).

Vancouver B2 Peri-Prosthetic Fractures in Cemented Femoral Implants can be Treated With Open Reduction and Internal Fixation Alone Without Revision

BACKGROUND

The aim of this study is to assess the outcomes of 52 consecutive Vancouver B2 peri-prosthetic fractures around cemented polished double-tapered stems treated by open reduction and internal fixation in 2 trauma centers in 2 countries.

METHODS

Outcomes included modified Harris Hip Score (mHHS), Harris Pain Score, and return to pre-injury mobility. Fracture healing was assessed; implant subsidence measured and complications including re-operations reported.

RESULTS

No patient was lost to follow-up. Median patient age at operation was 82 years (range 43-98); Harris pain scores showed minimal pain (median 42, range 10-44) at latest follow-up. Median total subsidence at 1 year was 1.1 mm (range 0-5.4), the majority of which occurred within the cement mantle. No subsequent femoral stem revision was required (median 2.9 years, 0-10); however, there were 3 re-operations: 1 re-operation for pre-existing recurrent dislocation involving head liner exchange and 2 for repeat fixation due to metal fatigue. Two additional fractures occurred below the new plating, requiring further plating whilst still retaining the original stems.

CONCLUSION

Anatomical reduction and open reduction and internal fixation of Vancouver B2 peri-prosthetic fractures should be considered as an appropriate treatment solution for frail elderly patients with a peri-prosthetic fracture around cemented polished double-tapered stems.