Objectives. Although many clinical and experimental investigations have shed light on muscle atrophy and intramuscular accumulation of fat after rotator cuff disruption, none have reported on their onset in the absence of muscle retraction. Methods. In 30 rabbits, we detached one supraspinatus (SSP) tendon and repaired it immediately, thus preventing muscle retraction. The animals were killed in groups of 10 at one, two and six weeks. Both shoulders of 15 non-operated rabbits served as controls. We measured the weight and volume of SSP muscles and quantified the cross-sectional area of intramuscular fat (i-fat) histologically. Results. There was significant loss of muscle weight and volume after one week (p = 0.004 and 0.003, respectively), and two weeks (both p < 0.001) in the experimental group; which recovered to control values after six weeks. I-fat accumulated one week after immediate repair, greater than in the control group and statistically significant at the mid-part of the muscle (mean 2.7% vs 1.5%, p = 0.008). I-fat continued to accumulate up to six weeks at all sites of the SSP muscle (all 3, p < 0.001). More fat accumulated closer to the musculotendinous junction than at the mid-part after two and six weeks (p = 0.012 and 0.019, respectively). Conclusion. Muscle atrophy and i-fat accumulation occur early after SSP tendon tear and immediate repair. While early repair benefitted muscle recovery, it did not prevent fat accumulation. SSP muscle retraction was not essential to the muscle alterations. The divergent evolution of muscle and fat points to different pathophysiologies. Cite this article: Bone Joint Res 2014;3:117–22

Introduction: Preliminary studies suggest that prolonged retraction of the paraspinal muscle during spinal surgery may produce ischaemic damage. We describe the continuous measurement of intramuscular pressures (IMP) during decompressive lumbar laminectomy and the relationship to back pain and disability. Methods: In this prospective interventional study, 28 patients undergoing surgery for lumbar canal stenosis were recruited. Back pain and function were assessed using the Visual Analogue Score (VAS), Oswestry Disability Index (ODI) and Short Form 36 (SF36) health survey. During surgery, IMP was continuously recorded from the multifidus muscle using a pressure transducer. The intramuscular perfusion pressure (IPP) was derived as the difference between the patient’s mean arterial pressure (MAP) and IMP (IPP = MAP − IMP). The data was analysed using repeated measures ANOVA (SPSS package). Results: The mean age was 60.4 ± 3 years and the mean duration of symptoms of 31.0 ± 6 months. The predominant symptoms were neurogenic claudication (14) and/or sciatica (13). Patients underwent 1 (N=3), 2 (N=20) or 3 (N=5) level laminectomies. The muscle retractors used were Norfolk and Norwich (N=16) and McCullock (N=12). The mean duration of deep muscle retraction was 68.5 ± 9 mins (range 19–240). On application of deep muscle retraction, there was a rapid and sustained increase in IMP (F=26.8; p< 0.001; repeated measures ANOVA), and overall the calculated mean IPP approached 0 mmHg or less during this period (F=36.8; p< 0.001). On release of deep muscle retraction there was a rapid decrease in IMP to pre-operative levels. The IPP was greater with Norfolk and Norwich than McCullock retractors (F=12.2; p< 0.001). Compared to pre-operative values, there was a decrease in ODI (F=18.6; p< 0.001) and VAS for back pain (F=9.9; p< 0.001) at discharge, 4–6 weeks and 6 months, post-operatively. Compared to pre-operative values, there was a decrease in SF36 scores at 6 months (F=26.7; p< 0.001). Total duration of muscle retraction over 60 mins was associated with higher VAS scores for back pain at 4–6 weeks and 6 months postoperatively (F=3.7; p< 0.01). There was no relationship between IPP and post-operative ODI or VAS for back pain. Conclusions: This study demonstrates a simple technique for the continuous monitoring of IMP during spinal surgery, from which the IPP can be derived. Comparison of two muscle retractors has shown that the McCullock retractor generates a higher IMP than Norfolk and Norwich retractor. Decompressive lumbar laminectomy improves the VAS for back pain and ODI and SF36 outcome scores in these patients. The results show that duration of muscle retraction, rather than extent of the pressure generated by the retractor, is related to postoperative back pain

Introduction: Anterior cervical spine surgeries are associated with high incidence (up to 60%) of early postoperative dysphagia and hoarseness of voice. These symptoms have been attributed to retraction injury on the larynx, trachea and oesophagus. Pressure from retractors producing ischaemia might explain the soft tissues complications following anterior cervical approach. Conventional retractor systems rely on the soft tissues for stability and create a vertical surgical channel but a novel system (Seex retractor) is fixed directly to the spine and rotates to allow an oblique approach. This may reduce retraction pressure by the Seex retractor on tissues This is the first investigation of retraction pressures using any two different retractor systems for anterior cervical spine surgery. The aims of this study were to measure the retraction pressure on the larynx, trachea and oesophagus during the anterior surgical approach to the cervical spine, in cadavers using conventional (Cloward) retractor and Seex retractor and to investigate the effect of flat or curved blades on retraction pressure. Methods: In a cadaveric model, through a standard anteriomedial approach simulated anterior cervical discectomy procedure was performed in cadavers at C3/4, C4/5, C5/6 and C6/7 levels using Cloward retractor with curved blade (Cervical Large Retractor Set. No. C50-1380: Cloward Instrument Corporation), Seex retractor with flat blade and Seex retractor with curved blade (Patent holder Dr. K. Seex, No PCT/AU05/001205). An online pressure transducer (Tekscan pressure measurement system) was applied between the retractor blade and medial tissues. Retraction pressures were recorded for all the retractors at each level on two separate occasions. Average retraction pressure (ARP), average peak retraction pressure (APRP), pressure distribution along the area of retraction, pressure difference at the edge and surface of the retractor blades, pressure variation with flat and curved blades were determined and compared. Results: A total of 40 sets of pressure recordings were made from 5 cadavers. Cloward retractor system generated an ARP of 33 mmHg (range 16 – 66 mmHg). ARP of Seex retractor with curved blade was 20 mmHg (range 9 – 50 mmHg) and that of Seex retractor with flat blade was 25 mmHg (range 10 – 74 mmHg). At one level ARP was same for all the three retractors. At another level ARP was same for Cloward retractor and Seex retractor with flat blade but higher than that of Seex retractor with curved blade. At two other levels Seex retractor with flat blade showed higher ARP than others. At 36 levels Cloward retractor showed highest ARP. This was statistically significant with Pearson’s Chi-square test (X2=10.023, degree of freedom=1, p = 0.0015) and Fisher exact test, p = 0.0005. Cloward retractor system showed an APRP of 124 mmHg (37 – 255 mmHg). While that of the Seex retractor with curved blade was 69 mmHg (14 – 254 mmHg) and that of Seex retractor with flat blade was 94 mmHg (18 – 255 mmHg). Of the 40 sets of the recordings at 32 levels Cloward retractor system generated highest APRP. With the Seex retractor itself flat blade generated more APRP than curved blade in 31 sets of measurements; it was reverse in 3 sets and in 6 sets APRP was same. Only at one level curved blade generated higher ARP than flat blade, at 11 levels it was same. At 28 levels ARP was higher with flat blade. Discussion: Cloward retractor generated significantly high retraction pressure (peak and average contact pressure) than Seex retractor in majority of the cases. Curved blades generate less retraction pressure than the flat ones. Based on these findings a prospective randomised study is underway in live patients

Background. Tears of the rotator cuff are a common pathology and poorly understood. Achieving a good functional outcome for patients may be difficult, and the degree of fat infiltration into the muscle is known to be a major determining factor to surgical repair and post operative function. It is the hypothesis of this study that the degree of retraction of the common central tendon as seen on MRI corresponds to the amount of fat infiltration classified according to the Goutallier grading System. Methods. MRI scans of the supraspinatus were reviewed and two groups identified: no tear (NT) and full thickness tear (FTT). The following measures were taken: central tendon retraction (CTR) and the Goutallier Grade according to MRI. The difference between Goutallier grade between NT and FTT were measured using the Mann-Whitney test. The relationship between Goutallier grade and increasing amount of CTR was described using Spearman's rank correlation and differences assessed using Mann-Whitney tests. Results. 143 scans had NT and 148 scans had FTT after exclusion and inclusion criteria were satisfied. All FTT involved the central tendon, with varying retraction. 143 in the NT group were Goutallier Grade 0–1. FTT revealed 2 Grade 0, 21 Grade 1, 35 Grade 2, 14 Grade 3, 76 Grade 4. The difference in Goutallier grade between the NT and FTT was highly significant (p<0.001). The increase in Goutallier grade associated with increasing retraction of the central tendon was also highly significant p<0.001. Conclusion. CTR can be directly linked to Goutallier grading and as such may help to determine surgical intervention between groups. Level of Evidence. Level 1 Diagnostic Study

Objectives. Acetabular retractors have been implicated in damage to the femoral and obturator nerves during total hip replacement. The aim of this study was to determine the anatomical relationship between retractor placement and these nerves. Methods. A posterior approach to the hip was carried out in six fresh cadaveric half pelves. Large Hohmann acetabular retractors were placed anteriorly, over the acetabular lip, and inferiorly, and their relationship to the femoral and obturator nerves was examined. Results. If contact with bone was not maintained during retractor placement, the tip of the anterior retractor had the potential to compress the femoral nerve by passing superficial to the iliopsoas. If pressure was removed from the anterior retractor, the tip pivoted on the anterior acetabular lip, and passed superficial to the iliopsoas, overlying and compressing the femoral nerve, when pressure was reapplied. The inferior retractor pierced the obturator membrane in all specimens medial to the obturator nerve, with subsequent retraction causing the tip to move laterally, making contact with the nerve. . Conclusion. Iliopsoas can only offer protection to the femoral nerve if the retractor passes deep to the muscle bulk. The anterior retractor should be reinserted if pressure is removed intra-operatively. Vigorous movement of the inferior retractor should be avoided. Cite this article: Bone Joint Res 2014;3:212–6

Introduction. Differing levels of tendon retraction are found in full-thickness rotator cuff tears. The pathophysiology of tendon degeneration and retraction is unclear. Neoangiogenesis in tendon parenchyma indicates degeneration. Hypoxia inducible factor 1(HIF) and vascular endothelial growth factor (VEGF) are important inducers of neoangiogenesis. Rotator cuff tendons rupture leads to fatty muscle infiltration (FI) and muscle atrophy (MA). The aim of this study is to clarify the relationship between HIF and VEGF expression, neoangiogenesis, FI, and MA in tendon retraction found in full-thickness rotator cuff tears. Methods. Rotator cuff tendon samples of 33 patients with full-thickness medium-sized rotator cuff tears were harvested during reconstructive surgery. The samples were dehydrated and paraffin embedded. For immunohistological determination of VEGF and HIF expression, sample slices were strained with VEGF and HIF antibody dilution. Vessel density and vessel size were determined after Masson-Goldner staining of sample slices. The extent of tendon retraction was determined intraoperatively according to Patte's classification. Patients were assigned to 4 categories based upon Patte tendon retraction grade, including one control group. FI and MA were measured on standardized preoperative shoulder MRI. Results. HIF and VEGF expression, FI, and MA were significantly higher in torn cuff samples compared with healthy tissue (p<0.05). HIF and VEGF expression, and vessel density significantly increased with extent of tendon retraction (p<0.04). A correlation between HIF/VEGF expression and FI and MA could be found (p<0.04). There was no significant correlation between HIF/VEGF expression and neovascularity (p>0.05). Conclusion. Tendon retraction in full-thickness medium-sized rotator cuff tears is characterized by neovascularity, increased VEGF/HIF expression, FI, and MA. VEGF expression and neovascularity may be effective monitoring tools to assess tendon degeneration

Purpose: Multiple deformations of the lower limbs are common orthopaedic complications of central nervous system disease. Assessment is difficult. Intrathecal Liorésal® was proposed for the patients to establish the relative effects of spasticity and musculotendinos retraction and define a medico-surgical therapeutic strategy. Material and methods: Between January 1999 and December 2000, 31 patients consulted for persistent knee flexion. Baclofen tests (75 – 100 μg Baclofen intrathecal) were performed in ten patients because the relative contribution of spasticity and retraction was difficult to assess. The anti-spasticity effect was observed within the first hour, with a maximal effect between the second and fourth hour. Motor function, joint motion, and function were tested during this time interval. The test was repeated approximately three days later, sometimes with higher doses depending on the level of the anti-spastic effect. Residual orthopaedic limitations were explained by musculotendinous retractions. Results: For the ten evaluated patients, three presented musculotendinous retractions amendable by surgical treatment (tendon lengthening, proximal disinsertion), sometimes in combination with arthrolysis. For the seven patients who had hypertonic spastic contractions, medical treatment was given with, for three patients, continuous intrathecal Lioresal via pump delivery. There was a correlation between the deformation assessed after the test and the test conducted under general anaesthesia during the procedure in all patients. Discussion: Other methods for evaluating orthopaedic deformities of the lower limbs can be used. Selective motor blocks using local anasethetics are generally reserved for patients with localised stiffness or when it may be difficult to achieve in certain patients (hip flexion). Mobilisation under general anaesthesia is another solution, but does not allow an assessment of functional gain, particularly if the goal is walking. The intrathecal Baclofen test not only allows an accurate assessment of orthopaedic retraction, but also an assessment of the functional impact of the spasticity, sometimes useful for verticalisation or walking. Conclusion: The Baclofen intrathecal test is a simple test with a particular place in the preoperative and functional assessment of neuro-orthpaedic stiffness of the lower limbs

Acetabular retractors have been implicated in damage to the femoral and obturator nerves during total hip arthroplasty (THA). Despite this association, the anatomical relationship between retractor and nerve has not been elucidated. A posterior approach to the hip was carried out in 6 fresh frozen cadaveric hemi- pelvises. Large Hohmann acetabular retractors were placed anteriorly over the acetabular rim, and inferiorly, as per routine practice in THA. The femoral and obturator nerves were identified through dissection and their relationship to the retractors was examined. If contact with bone was not maintained during retractor placement, the tip of the anterior retractor had the potential to compress the femoral nerve, by passing either superficial to, or through the bulk of the iliopsoas muscle. If pressure was removed from the anterior retractor, the tip pivoted on the anterior acetabular lip, and passed superficial to iliopsoas, overlying and compressing the femoral nerve, when pressure was reapplied. The inferior retractor pierced the obturator membrane, medial to the obturator foramen in all specimens. Subsequent retraction resulted in the tip moving laterally to contact the obturator nerve. Both the femoral and obturator nerves are vulnerable to injury around the acetabulum through the routine placement of retractors in THA. The femoral nerve is vulnerable where it passes over the anterior acetabulum. Iliopsoas can only offer protection if the retractor passes deep to the muscle bulk. If pressure is removed from the anterior retractor intra-operatively it should be reinserted. The obturator nerve is vulnerable as it exits the pelvis through the obturator foramen. Vigorous movement of the inferior retractor should be avoided. Awareness of the anatomy around the acetabulum is essential when placing retractors

Purpose: Although hamstring retraction is a frequent complication of spastic hypertoniq, very few series have been reported in adults. The purpose of this study was to evaluate results of therapeutic modalities proposed: distal hamstring tenotomy and use of an external fixator in case of permanent knee flexion. Material and methods: This retrospective series included 37 cerebral palsy patients, 59 with permanent knee flexion. Mean flexion was 69° (20–130°). Mean motion was 61° (10–100°). Deformation of the supra and infra joints was present in 82%. There were 22 patients with bilateral permanent knee flexion. Simple tenotomy of the sartorius, the semitendinous and the gracilis with lengthenings of the semimembranous and biceps. Disinsertion of the gastrocnemius and section of posterior aponeurosis were associated as needed. Postoperative immobilization was achieved with a Zimmer cast in case of moderate flexion and with an external femorotibial fixator in case of major deformation. Postoperative rehabilitation exercises performed several times daily were initiated in all patients. Results: At mean follow-up of 641 days, residual flexion was 6° (0–40°) and mean joint motion was 111°. All knees were stable. Three dehiscent wounds required surgical repair. The function objective, established pre-operatively, was achieved or exceeded. Discussion: When postoperative immobilization is necessary, external fixation limits cutaneous risks and facilitates rehabilitation. It appears to be better than successive cases. Unlike other authors, we did not find section of the posterior cruciate ligament to be necessary. Conclusion: Distal hamstring tenotomy associated with postoperative immobilization with an external fixator is a reliable and effective technique for the treatment of permanent knee flexion in cerebral palsy adults

Orthopaedic joint replacement surgery requires surgical assistants holding retractors in order to adequately visualise the operative field. Typically, total hip and knee replacement operations require at least one surgical assistant and preferably two. As such, tremendous resources are consumed in order to perform elective TJA.

A mechanised pulley system, called the Gripper (Medenvision, Belgium), has been devised to assist with this need for extra “hands” to hold retractors. The Gripper is a table mounted, disposable device used to hold retractors, and is infinitely adjustable with regard to position in space. As such, it can be used in a variety of situations to provide an additional retractor holder, without the need for extra manpower. It is sterile, in the operative field, and can fit retractors with a flat handle. With positioning of the table mounts before prepping and draping, the Gripper can be used during the operation to hold retractors that would otherwise require a surgical assistant. The Gripper can be moved around during different portions of the operation in order to make the most of it use.

In our experience, the Gripper has been most useful in direct anterior approach THA, holding a curved anterior retractor to facilitate acetabular exposure. It is also useful in holding a retractor placed over the tip of the greater trochanter during femoral preparation. In our estimation, it is able to replace a human surgical assistant at a fraction of the cost. Furthermore, the Gripper does not fatigue during the operation and does not compromise the surgical field by needing to adjust its handhold. Because of this, even in an academic center with residents, fellows, and visiting medical students, the Gripper is preferable to human hands holding retractors.

We estimate that a surgical assistant with a starting level salary would have to scrub in on over 300 cases per year in order to make him/herself more cost effective than the Gripper.

Objectives. Despite the fact that research fraud and misconduct are under scrutiny in the field of orthopaedic research, little systematic work has been done to uncover and characterise the underlying reasons for academic retractions in this field. The purpose of this study was to determine the rate of retractions and identify the reasons for retracted publications in the orthopaedic literature. Methods. Two reviewers independently searched MEDLINE, EMBASE, and the Cochrane Library (1995 to current) using MeSH keyword headings and the ‘retracted’ filter. We also searched an independent website that reports and archives retracted scientific publications (. www.retractionwatch.com. ). Two reviewers independently extracted data including reason for retraction, study type, journal impact factor, and country of origin. Results. One hundred and ten retracted studies were included for data extraction. The retracted studies were published in journals with impact factors ranging from 0.000 (discontinued journals) to 13.262. In the 20-year search window, only 25 papers were retracted in the first ten years, with the remaining 85 papers retracted in the most recent decade. The most common reasons for retraction were fraudulent data (29), plagiarism (25) and duplicate publication (20). Retracted articles have been cited up to 165 times (median 6; interquartile range 2 to 19). Conclusion. The rate of retractions in the orthopaedic literature is increasing, with the majority of retractions attributed to academic misconduct and fraud. Orthopaedic retractions originate from numerous journals and countries, indicating that misconduct issues are widespread. The results of this study highlight the need to address academic integrity when training the next generation of orthopaedic investigators. Cite this article: J. Yan, A. MacDonald, L-P. Baisi, N. Evaniew, M. Bhandari, M. Ghert. Retractions in orthopaedic research: A systematic review. Bone Joint Res 2016;5:263–268. DOI: 10.1302/2046-3758.56.BJR-2016-0047

This technique is a novel superior based muscle sparing approach. Acetabular reaming in all hip approaches requires femoral retraction. This technique is performed through a hole in the lateral femoral cortex without the need to retract the femur. A 5 mm hole is drilled in the lateral femur using a jig attached to the broach handle, similar to a femoral nail. Specialised instruments have been developed, including a broach with a hole going through it at the angle of the neck of the prosthesis, to allow the rotation of the reaming rod whilst protecting the femur. A special C-arm is used to push on the reaming basket. The angle of the acetabulum is directly related to the position of the broach inside the femoral canal and the position of the leg. A specialised instrument allows changing of offset and length without dislocating the hip during trialling. Some instrumentation has been used in surgery but ongoing cadaver work is being performed for proof of concept. The ability to ream through the femur has been proven during surgery. The potential risk to the bone has been assessed using finite analysis as minimal. The stress levels for any diameter maintained within a safety factor >4 compared to the ultimate tensile strength of cortical bone. The described technique allows for transfemoral acetabular reaming without retraction of the femur. It is minimally invasive and simple, requiring minimal assistance. We are incorporating use with a universal robot system as well as developing an electromagnetic navigation system. Assessment of the accuracy of these significantly cheaper systems is ongoing but promising. This approach is as minimally invasive as is possible, safe, requires minimal assistance and has a number of other potential advantages with addition of other new navigation and simple robotic attachments

Aims. Rotator cuff (RC) injuries are characterized by tendon rupture, muscle atrophy, retraction, and fatty infiltration, which increase injury severity and jeopardize adequate tendon repair. Epigenetic drugs, such as histone deacetylase inhibitors (HDACis), possess the capacity to redefine the molecular signature of cells, and they may have the potential to inhibit the transformation of the fibro-adipogenic progenitors (FAPs) within the skeletal muscle into adipocyte-like cells, concurrently enhancing the myogenic potential of the satellite cells. Methods. HDACis were added to FAPs and satellite cell cultures isolated from mice. The HDACi vorinostat was additionally administered into a RC injury animal model. Histological analysis was carried out on the isolated supra- and infraspinatus muscles to assess vorinostat anti-muscle degeneration potential. Results. Vorinostat, a HDACi compound, blocked the adipogenic transformation of muscle-associated FAPs in culture, promoting myogenic progression of the satellite cells. Furthermore, it protected muscle from degeneration after acute RC in mice in the earlier muscle degenerative stage after tenotomy. Conclusion. The HDACi vorinostat may be a candidate to prevent early muscular degeneration after RC injury. Cite this article: Bone Joint Res 2024;13(4):169–183

As the intervertebral disc is largely avascular, needle injection is the most practical method for delivery of therapeutic agents used in treatments for degenerative disc disease. Intradiscal pressure increases during injection, and insufficient recovery time prior to needle retraction may result in injectate leakage. In order to determine the maximum pressure and post-injection recovery time for a given injection volume and rate, an analytical model of intradiscal injection was developed and calibrated experimentally. A governing equation was derived defining intradiscal pressure as a function of effective permeability, initial elastic stiffness, nonlinear stiffness term, and injection rate. The equation was solved using a fourth order Runge-Kutta routine with a 0.05s time step and a ramp-dwell injection. The model was calibrated by performing controlled intradiscal injections on five bovine caudal intervertebral discs. Three had adjacent vertebrae intact, while two were separated from vertebrae and constrained between porous stainless steel platens. A syringe driven by a linear actuator was used to inject phosphate buffered saline through a 21g hypodermic needle inserted radially into the disc to a depth of one half of the disc diameter. Injection was performed at a rate of 75μL/s to a volume of 250μL followed by a 240s dwell. Fluid pressure was recorded during both the injection phase and subsequent recovery phase. For each experimental pressure vs time trace, model parameters were varied in order to obtain an optimal fit. The model was run with the average parameter values across a grid of possible injection protocols, with injection volume ranging from 30 to 300μL and injection time ranging from 0.1 to 5s. For each case, peak pressure and time required to reach a 1kPa threshold were recorded. Experimentally measured peak pressure ranged from 68 to 88kPa. Pressure at the end of the 240s dwell ranged from 49 to 69kPa. There was no apparent difference between discs with and without endplates. Leakage of fluid following needle retraction was observed in all specimens. Experimental data were well fit by the analytical model, which predicted higher peak pressure and longer recovery time with increasing volume, from approximately 1500s at 30μL to nearly 3000s at 300μL. The model was nearly insensitive to injection rate. The experimental data confirm pressurization of the disc during injection and injectate leakage resulting from insufficient recovery time. The model predicts that the time required to recover to below threshold leakage pressure is impractically long for both laboratory and clinical injection protocols. Similar behavior with and without endplates confirms that fluid flow is limited by permeability of the tissue itself, not the boundary conditions. Slow recovery is likely attributable to the fact that peak injection pressures were lower than the hydraulic swelling pressure of the nucleus pulposus, which has been reported to be approximately 140kPa. Due to the high swelling pressure of the nucleus pulposus, it is unlikely that intradiscal injection procedures can be performed without substantial injectate leakage following needle retraction

Aims. Fracture-related infection (FRI) is commonly classified based on the time of onset of symptoms. Early infections (< two weeks) are treated with debridement, antibiotics, and implant retention (DAIR). For late infections (> ten weeks), guidelines recommend implant removal due to tolerant biofilms. For delayed infections (two to ten weeks), recommendations are unclear. In this study we compared infection clearance and bone healing in early and delayed FRI treated with DAIR in a rabbit model. Methods. Staphylococcus aureus was inoculated into a humeral osteotomy in 17 rabbits after plate osteosynthesis. Infection developed for one week (early group, n = 6) or four weeks (delayed group, n = 6) before DAIR (systemic antibiotics: two weeks, nafcillin + rifampin; four weeks, levofloxacin + rifampin). A control group (n = 5) received revision surgery after four weeks without antibiotics. Bacteriology of humerus, soft-tissue, and implants was performed seven weeks after revision surgery. Bone healing was assessed using a modified radiological union scale in tibial fractures (mRUST). Results. Greater bacterial burden in the early group compared to the delayed and control groups at revision surgery indicates a retraction of the infection from one to four weeks. Infection was cleared in all animals in the early and delayed groups at euthanasia, but not in the control group. Osteotomies healed in the early group, but bone healing was significantly compromised in the delayed and control groups. Conclusion. The duration of the infection from one to four weeks does not impact the success of infection clearance in this model. Bone healing, however, is impaired as the duration of the infection increases. Cite this article: Bone Joint Res 2024;13(3):127–135

Background. RHF nail is an important tool for simultaneous ankle and subtalar joint stabilisation +/− fusion. Straight and curved RHF nails are available to use, but both seem to endanger plantar structures, especially the lateral plantar artery and nerve and Baxter's nerve. There is a paucity of literature on the structures at risk with a straight RHF nail inserted along a line bisecting the heel pad and the second toe (after Stephenson et al). In this study, plantar structures ‘at risk’ were studied in relation to a straight nail inserted as above. Methods. Re-creating real-life conditions and strictly following the recommended surgical technique with regards to the incision and guide-wire placement, we inserted an Orthosolutions Oxbridge nail into the tibia across the ankle and subtalar joints in 6 cadaveric specimens. Tissue flaps were then raised to expose the heel plantar structures and studied their relation to the inserted nail. Results. The medial plantar artery and nerve were always more than 10mm away from the medial edge of the nail, while the Baxter nerve was a mean 14mm behind. The lateral plantar nerve was a mean 7mm medial to the nail, while the artery was a mean 2.3mm away with macroscopic injury in one specimen. The other structures ‘at risk’ were the plantar fascia and small foot muscles. Conclusion. Lateral plantar artery and nerve are the most vulnerable structures during straight RHF nailing. The risk to heel plantar structures could be mitigated by making incisions longer, blunt dissection down to bone, meticulous retraction of soft tissues and placement of the protection sleeve down to bone to prevent the entrapment of plantar structures during guide-wire placement, reaming and nail insertion

Massive posterosuperior cuff tears (mRCT) retracted to the glenoid are surgically challenging and often associated with high retear rates. Primary repair is a less-favourable option and other salvage procedures such as SCR and tendon transfers are used. This study presents clinical and radiological outcomes of muscle advancement technique for repair of mRCT. Sixty-one patients (mean age 57±6, 77% males and 23% females) (66 shoulders) underwent all-arthroscopic rotator cuff repair that included supraspinatus and infraspinatus subperiosteal dissection off scapular bony fossae, lateral advancement of tendon laminae, and tension-free double-layer Lasso Loop repair to footprint. Pre-and post-operative range of motion (ROM), cuff strength, VAS, Constant, ASES, and UCLA scores were assessed. Radiologic assessment included modified Patte and Goutallier classifications. All patients had MRI at 6 months to evaluate healing and integrity of repair was assessed using Sugaya classification with Sugaya 4 and 5 considered retears. Advanced fatty degeneration (Goutallier 3-4) was present in 44% and 20% of supraspinatus and infraspinatus. Tendon retraction was to the level of or medial to glenoid in 22%, and just lateral in 66%. 50.8% mRCT extended to teres minor. Subscapularis was partially torn (Lafosse 1-3) in 46% and completely torn (Lafosse 4-5) in 20%. At mean follow-up (52.4 weeks), a significant increase in ROM, Relative Cuff Strength (from 57% to 90% compared to contralateral side), VAS (from 4 ±2.5 to 1±1.7), Constant (50±17.8 to 74 ±13.0), ASES (52 ±17.5 to 87 ±14.9), and UCLA (16± 4.9 to 30 ±4.9) scores were noted. There were six retears (10%), one failure due to P. acnes infection. 93% returned to pre-injury work and 89% of cases returned to pre-injury sport. Satisfaction rate was 96%. Muscle advancement technique for mRCT is a viable option with low retear rates, restoration of ROM, strength, and excellent functional outcomes

Analyzing shoulder kinematics is challenging as the shoulder is comprised of a complex group of multiple highly mobile joints. Unlike at the elbow or knee which has a primary flexion/extension axis, both primary shoulder joints (glenohumeral and scapulothoracic) have a large range of motion (ROM) in all three directions. As such, there are six degrees of freedom (DoF) in the shoulder joints (three translations and three rotations), and all these parameters need to be defined to fully describe shoulder motion. Despite the importance of glenohumeral and scapulothoracic coordination, it's the glenohumeral joint that is most studied in the shoulder. Additionally, the limited research on the scapulothoracic primarily focuses on planar motion such as abduction or flexion. However, more complex motions, such as internally rotating to the back, are rarely studied despite the importance for activities of daily living. A technique for analyzing shoulder kinematics which uses 4DCT has been developed and validated and will be used to conduct analysis. The objective of this study is to characterize glenohumeral and scapulothoracic motion during active internal rotation to the back, in a healthy young population, using a novel 4DCT approach. Eight male participants over 18 with a healthy shoulder ROM were recruited. For the dynamic scan, participants performed internal rotation to the back. For this motion, the hand starts on the abdomen and is moved around the torso up the back as far as possible, unconstrained to examine variability in motion pathway. Bone models were made from the dynamic scans and registered to neutral models, from a static scan, to calculate six DoF kinematics. The resultant kinematic pathways measured over the entire motion were used to calculate the ROM for each DoF. Results indicate that anterior tilting is the most important DoF of the scapula, the participants all followed similar paths with low variation. Conversely, it appears that protraction/retraction of the scapula is not as important for internally rotating to the back; not only was the ROM the lowest, but the pathways had the highest variation between participants. Regarding glenohumeral motion, internal rotation was by far the DoF with the highest ROM, but there was also high variation in the pathways. Summation of ROM values revealed an average glenohumeral to scapulothoracic ratio of 1.8:1, closely matching the common 2:1 ratio other studies have measured during abduction. Due to the unconstrained nature of the motion, the complex relationship between the glenohumeral and scapulothoracic joints leads to high variation in kinematic pathways. The shoulder has redundant degrees of freedom, the same end position can result from different joint angles and positions. Therefore, some individuals might rely more on scapular motion while others might utilize primarily humeral motion to achieve a specific movement. More analysis needs to be done to identify if any direct correlations can be drawn between scapulothoracic and glenohumeral DoF. Analyzing the kinematics of the glenohumeral and scapulothoracic joint throughout motion will further improve understanding of shoulder mechanics and future work plans to examine differences with age