Dislocation is one of the most common complications in total hip arthroplasty (THA) and is primarily driven by bony or prosthetic impingement. The aim of this study was two-fold. First, to develop a simulation that incorporates the functional position of the femur and pelvis and instantaneously determines range of motion (ROM) limits. Second, to assess the number of patients for whom their functional bony alignment escalates impingement risk.

468 patients underwent a preoperative THA planning protocol that included functional x-rays and a lower limb CT scan. The CT scan was segmented and landmarked, and the x-rays were measured for pelvic tilt, femoral rotation, and preoperative leg length discrepancy (LLD). All patients received 3D templating with the same implant combination (Depuy; Corail/Pinnacle). Implants were positioned according to standardised criteria.

Each patient was simulated in a novel ROM simulation that instantaneously calculates bony and prosthetic impingement limits in functional movements. Simulated motions included flexion and standing-external rotation (ER). Each patient's ROM was simulated with their bones oriented in both functional and neutral positions.

13% patients suffered a ROM impingement for functional but not neutral extension-ER. As a result, 48% patients who failed the functional-ER simulation would not be detected without consideration of the functional bony alignment. 16% patients suffered a ROM impingement for functional but not neutral flexion. As a result, 65% patients who failed the flexion simulation would not be detected without consideration of the functional bony alignment.

We have developed a ROM simulation for use with preoperative planning for THA surgery that can solve bony and prosthetic impingement limits instantaneously. The advantage of our ROM simulation over previous simulations is instantaneous impingement detection, not requiring implant geometries to be analysed prior to use, and addressing the functional position of both the femur and pelvis.

Iliopsoas tendonitis occurs in up to 30% of patients after hip resurfacing arthroplasty (HRA) and is a common reason for revision. The primary purpose of this study was to validate our novel computational model for quantifying iliopsoas impingement in HRA patients using a case-controlled investigation. Secondary purpose was to compare these results with previously measured THA patients.

We conducted a retrospective search in an experienced surgeon's database for HRA patients with iliopsoas tendonitis, confirmed via the active hip flexion test in supine, and control patients without iliopsoas tendonitis, resulting in two cohorts of 12 patients. The CT scans were segmented, landmarked, and used to simulate the iliopsoas impingement in supine and standing pelvic positions. Three discrete impingement values were output for each pelvic position, and the mean and maximum of these values were reported. Cup prominence was measured using a novel, nearest-neighbour algorithm.

The mean cup prominence for the symptomatic cohort was 10.7mm and 5.1mm for the asymptomatic cohort (p << 0.01). The average standing mean impingement for the symptomatic cohort was 0.1mm and 0.0mm for the asymptomatic cohort (p << 0.01). The average standing maximum impingement for the symptomatic cohort was 0.2mm and 0.0mm for the asymptomatic cohort (p << 0.01). Impingement significantly predicted the probability of pain in logistic regression models and the simulation had a sensitivity of 92%, specificity of 91%, and an AUC ROC curve of 0.95.

Using a case-controlled investigation, we demonstrated that our novel simulation could detect iliopsoas impingement and differentiate between the symptomatic and asymptomatic cohorts. Interestingly, the HRA patients demonstrated less impingement than the THA patients, despite greater cup prominence. In conclusion, this tool has the potential to be used preoperatively, to guide decisions about optimal cup placement, and postoperatively, to assist in the diagnosis of iliopsoas tendonitis.

Iliopsoas impingement occurs in between 5-30% of patients after hip arthroplasty and has been thought to only be caused by an oversized cup, cup malpositioning, or the depth of the psoas valley. However, no study has associated the relationship between preoperative measurements with the risk of impingement. This study sought to assess impingement between the iliopsoas and acetabular cup using a novel validated model to determine the risk factors for iliopsoas impingement.

413 patients received lower limb CT scans and lateral x-rays that were segmented, landmarked, and measured using a validated preoperative planning protocol. Implants were positioned according to the preference of ten experienced surgeons. The segmented bones were transformed to the standing reference frame and simulated with a novel computational model that detects impingement between the iliopsoas and acetabular cup. Definitions of patients at-risk and not at-risk of impingement were defined from a previous validation study of the simulation. At-risk patients were propensity score matched to not at-risk patients.

21% of patients were assessed as being at-risk of iliopsoas impingement. Significant differences between at-risk patients and not at-risk patients were observed in standing pelvic tilt (p << 0.01), standing femoral internal rotation (p << 0.01), medio-lateral centre-of-rotation (COR) change (p << 0.01), supine cup anteversion (p << 0.01), pre- to postoperative cup offset change (p << 0.001), postoperative gross offset (p = 0.009), and supero-inferior COR change (p = 0.02).

Impingement between the iliopsoas and acetabular cup is under-studied and may be more common than is published in the literature. Previously it has been thought to only be related to cup size or positioning. However, we have observed significant differences between at-risk and not at-risk patients in additional measurements. This indicates that its occurrence is more complex than simply being related to cup position.

In 2021, Vigdorchik et al. published a large multicentre study validating their simple Hip-Spine Classification for determining patient-specific acetabular component positioning in total hip arthroplasty (THA). The purpose of our study was to apply this Hip-Spine Classification to a sample of Australian patients undergoing THA surgery to determine the local acetabular component positioning requirements. Additionally, we propose a modified algorithm for adjusting cup anteversion requirements.

790 patients who underwent THA surgery between January 2021 and June 2022 were assessed for anterior pelvic plane tilt (APPt) and sacral slope (SS) in standing and relaxed seated positions and categorized according to their spinal stiffness and flatback deformity. Spinal stiffness was measured using pelvic mobility (PM); the ΔSS between standing and relaxed seated. Flatback deformity was defined by APPt <−13° in standing. As in Vigdorchik et al., PM of <10° was considered a stiff spine. For our algorithm, PM of <20° indicated the need for increased cup anteversion. Using this approach, patient-specific cup anteversion is increased by 1° for every degree the patient's PM is <20°.

According to the Vigdorchik simple Hip-Spine classification groups, we found: 73% Group 1A, 19% Group 1B, 5% Group 2A, and 3% Group 2B. Therefore, under this classification, 27% of Australian THA patients would have an elevated risk of dislocation due to spinal deformity and/or stiffness. Under our modified definition, 52% patients would require increased cup anteversion to address spinal stiffness.

The Hip-Spine Classification is a simple algorithm that has been shown to indicate to surgeons when adjustments to acetabular cup anteversion are required to account for spinal stiffness or flatback deformity. We investigated this algorithm in an Australian population of patients undergoing THA and propose a modified approach: increasing cup anteversion by 1° for every degree the patient's PM is <20°.

Aims

Iliopsoas impingement occurs in 4% to 30% of patients after undergoing total hip arthroplasty (THA). Despite a relatively high incidence, there are few attempts at modelling impingement between the iliopsoas and acetabular component, and no attempts at modelling this in a representative cohort of subjects. The purpose of this study was to develop a novel computational model for quantifying the impingement between the iliopsoas and acetabular component and validate its utility in a case-controlled investigation.

Aims

Leg length discrepancy (LLD) is a common pre- and postoperative issue in total hip arthroplasty (THA) patients. The conventional technique for measuring LLD has historically been on a non-weightbearing anteroposterior pelvic radiograph; however, this does not capture many potential sources of LLD. The aim of this study was to determine if long-limb EOS radiology can provide a more reproducible and holistic measurement of LLD.

Total hip arthroplasty (THA) continues moving to the outpatient arena, and may be feasible for some conversion and revision scenarios. Controversy surrounds appropriate patient selection. The purpose of this study is to report complications associated with outpatient revision and conversion THA, and to determine if comorbidities are associated with complications or overnight stay.

From June 2013 through March 2018, 43 patients (44 hips) underwent conversion (n=12) or revision (n=32) THA at a free-standing ambulatory surgery center. Mean patient age was 58.4 years, and 52% of patients were male. Conversion procedures were for failed resurfacing in two, failed hemiarthroplasty in one, and failed fracture fixation with retained hardware in 9. Revision procedures involved head only in one, head and liner in 20, cup and head in 7, stem only in 2, and stem and liner in 2.

Forty-four (93%) were discharged same day without incident, none required transfer to acute facility, and 3 required overnight stay with 2 of these for convenience and only one for a medical reason, urinary retention. Three patients with early superficial infection were successfully treated with oral antibiotics. There were no major complications, readmissions, or subsequent surgeries within 90 days. One or more major comorbidities were present in 17 patients (39%) including 1 valvular disease, 8 arrhythmia, 2 thromboembolism history, 3 obstructive sleep apnea, 6 chronic obstructive pulmonary disease, 2 asthma, 4 frequent urination, and 1 renal disease. The single patient who stayed overnight for a medical reason had no major medical comorbidities.

Outpatient arthroplasty, including revision THA in some scenarios, is safe for many patients. Presence of medical comorbidities was not associated with risk of complications. The paradigm change of patient education, medical optimization, and a multimodal program to mitigate risk of blood loss and reduce need for narcotics facilitates performing arthroplasty safely in an outpatient setting.

Introduction

The Intellijoint HIP system is a mini-optical navigation system designed to intraoperatively assist with cup orientation, leg length and offset in total hip replacement (THR). As with any imageless navigation system, acquiring the pelvic reference frame intraoperatively requires assumptions. The system does however have the ability to define the native acetabular orientation intra-operatively by registering 3-points along the bony rim. In conjunction with a pre-operative CT scan, the authors hypothesised that this native acetabular plane could be used as an intraoperative reference to achieve a planned patient-specific cup orientation.

Financial impact and patient satisfaction with four different anticoagulants for hip and knee arthroplasty in patients with a previous history of VTE- A prospective randomised trial

Background: Subacromial decompression surgery is associated with significant postoperative pain. We compared the effect of intrascalene block (ISB) and sub-acromial bursa block (SBB) with simple opiate based analgesia

Methods: In a prospective, randomised controlled trial, fifty-three (n = 53) patients scheduled for arthroscopic subacromial decompression were randomised into three groups receiving Intrascalene block (n =19), Subacromial Bursa block (n =19) or neither of the two blocks (n =15 controls). Patients with cuff pathology were excluded. ISB was performed preoperatively with 20 mls of 1% Prilocaine and 10 mls of 0.5 % Bupivacaine. SBB was given with 20 mls of 0.5% Bupivacaine postoperatively. All patients received standardised general anaesthetic and postoperative analgesia. Pain, sickness and sedation scores were noted at 1, 2, 4, 8, 12 and 24 hours postoperatively. The postoperative consumption of morphine and the time when the first bolus of morphine was required were also noted.

Results: The visual analogue pain scores in the ISB and SBB group were lower than the control group in the first twelve hours postoperatively achieving statistical significance but there were no significant differences between the SBB and ISB groups. The controls consumed more morphine postoperatively (mean 32.3 mls) than SBB (21.21 mls) and ISB groups (14.00 mls) (p < 0.001). The time for first bolus was earlier in the controls (mean 30.2 mins) as compared to both SBB (72.7 mins) and ISB groups (105.8 mins) (p< 0.001). The oral analgesic intake was less in the SBB and ISB groups than the controls (p = 0.004), but there was no difference between the two treatment groups.

Conclusion: Whilst intrascalene block remains the gold standard where expertise is available for its administration, subacromial bursa block is a safe alternative in patients with intact rotator cuff undergoing arthroscopic subacromial decompression.

CTEV is a difficult condition to treat with chances of recurrence, re-operation rate and over correction. Recent literature based on evidence is favourable with the Ponseti management. The aim of the study was to review our surgical results over a 5-year period using the Cincinnati approach.

Children with failure of conservative serial stretching and casting for 6 months underwent open release. The records and radiographs were reviewed retrospectively from 1997–2002. 60 patients were identified with 92 feet undergoing primary sub radical releases using the Cincinnati approach in 40 male and 20 female children. The mean age at surgery was 10 months. 55 patients were idiopathic with 3 syndromal and 2 teratological.

Consultants performed > 75% of operations, with k-wire stabilisation done in 46 patients and primary wound closure in 25; the majority of wounds were left open. The timing of plaster change varied, with the majority at 2 weeks. Wound problems occurred in 4 patients (significant in 2). All patients but one wore splints for an average length of 13 months. Complication rate was 20% comprising infection, over- correction and recurrence. Re-operation rate for early recurrence was 12%. Further surgery in the form of tibialis anterior transfer and derotation osteotomy was performed on 15% and 10% of feet respectively. 6 feet in 4 patients showed signs of significant over correction.

Wound healing by secondary intention of the Cin-cinnati approach is safe. Results and complications are comparable to other series, but not to the Ponseti non-operative management. Practice is now changed to the latter based on evidence.

Introduction: The ‘gold standard’ currently used to assess bone quality is bone mineral density (BMD) measured by Dual Energy X-ray Absorptiometry (DEXA). However BMD accounts for no more than 60 – 70% of bone strength. X-rays are affected primarily by the mineral phase of bone; the organic phase remains essentially invisible. Yet it is known that the material strength and toughness of bone is critically dependent on its organic phase. A Raman spectroscopic technique was used that permitted visualisation of both phases of bone deep to unbroken skin by successfully removing spectral information from the overlying tissues.

Hypothesis: Spectral features of both the mineral and organic phases of bone from different murine genotypes can be measured objectively through the unbroken skin using time-resolved Raman spectroscopy.

Methods: We used an 800 nm probe laser (1 kHz, 1 ps pulses, focussed to 1 mm diameter) with a synchronised 4 ps optical Kerr gate that had a variable picosecond delay that effectively shuttered out photons from the overlying tissues. We measured bone spectra at a point 2mm above the carpus from two mouse genotypes: wildtype and oim/oim (matched for age, sex and weight) at a typical depth 1.1mm. We then repeated the measurements once the overlying tissues had been carefully removed to expose the bones directly. Oim/oim mice produce only homotrimeric collagen I, (á1(I)3), associated with this change in collagen is a poor mineralisation of the bone tissue, making it an ideal model for a this study.

Results: We recorded the main spectral features in both phases of bone and showed that the ratios of spectral bands from the two phases were similar within each genotype, whether measured through the skin or directly from exposed bone. However, there was a significant difference in the same ratios between genotypes associated with a reduced mineralisation in the oim/oim mice; a significant difference that was apparent both directly from bone and through skin. The band associated with CH2 wag of collagen (organic phase) showed a frequency shift between the genotypes.

Discussion: Measurements of the spectra and their analysis were similar whether made directly on bone or transcutaneously. We were able to detect changes in mineralisation between genotypes and, unlike measurements of BMD, we showed also changes in collagen. Since the material strength of bone is critically dependent on collagen, this indicates an appreciable advantage of this technique over DEXA.

Conclusions: This novel technique allowed objective transcutaneous spectral measurements of bone tissue and was able to distinguish between normal and unhealthy bone tissue. With a laser focussed to 1 mm diameter that was readily moveable, these measurements were specific to that site (2 mm proximal to the carpus). After further optimisation, this technology is likely to improve fracture risk assessments in comparison to the use of DEXA alone, opening opportunities for screening in anticipation of the predicted increase in fragility fractures.

Aims: To investigate the optimal dimension interference screw for fixation of a tendon graft in a bone tunnel. Methods: A porcine model was developed to represent ACL reconstruction in the distal femur. A standard 8mm size pig flexor tendon graft was inserted into a standard 8mm bone tunnel. The screw dimensions were varied. The tendon was loaded with a constant force using a Universal Testing Machine. The construct was tested to failure at a rate of 50mm/minute. Load, deformation data and mechanism of construct failure were recorded. The screw diameters of 7, 8 and 9mm and lengths of 20, 25 and 30mm were tested in 80 individual reconstructions. Results: The mean pull out force was similar between the 7mm (191N) and 8mm screws (188N), but significantly different for the 9mm screw (109N) (p< 0.05) The 30mm screw (231N) was marginally better than the 20mm screw (215N) (p> 0.05). The mechanism of failure however, was significantly different between the groups. All grafts fixed with a 9mm screw failed at the tunnel opening (100%), whereas those fixed with a 7mm screw failed by slippage of the graft along the length of the tunnel (83%). The screw length did not affect the mechanism of graft failure. Conclusion: Our results suggest that a screw size equal to or 1mm less than the diameter of the tunnel gives the optimum initial interference screw fixation of tendon in a bone tunnel.

We studied prospectively the relationship between serum lipids and Dupuytren's disease of the hand in 85 patients, 65 men and 20 women. The Dupuytren patients had significantly higher fasting serum cholesterol and triglyceride levels than did the controls (p < 0.001). The raised levels of serum lipids appeared to be associated with the pathogenesis of Dupuytren's disease, and this may help to explain the high incidence of Dupuytren's disease in alcoholic, diabetic and epileptic patients, since these conditions are also associated with raised serum lipid levels.