Introduction. Symptomatic hip dysplasia is often treated with periacetabular osteotomy (PAO). Studies investigating the effect of PAO have primarily focused on radiographic measurements, pain-related outcomes, and hip survival whereas evidence related to sport participation is limited. Methods. All patients in our institutional database were deemed eligible for this cohort study if they underwent PAO and had answered at least one question related to sport participation. Patients were asked if they were playing sport preoperatively, 6 months after PAO as well as 2, 5, 10, 15 and 20 years after. In addition, patients were asked if they were able to play their preferred sport, what type and at what level they were playing sport, and if surgery had improved their sport performance. Results. Among 2398 patients surveyed, 1926 (80%) were included and 56% were playing sport 6 months after PAO. This number was 61% two years after PAO, and remained around that for the following years, before dropping 15 years after PAO. Between 56% and 71% of patients felt that their sporting performance improved following PAO at the different time points. Between 39% (6 months after PAO) and 63% (15 years after PAO) were able to participate in their preferred sport. Conclusion. The majority of patients undergoing PAO due to hip dysplasia will return to, and maintain, sport after PAO. More than half of patients undergoing PAO believe that the surgery improved their sports performance, and long after the surgery more than half of patients undergoing PAO are able to play their preferred sport

Abstract. OBJECTIVES. Although surgical periacetabular osteotomy (PAO) for hip dysplasia aims to optimise acetabular coverage and restore hip function, it is unclear how surgery affects capsular mechanics and joint stability. The purpose was to examine how the reoriented acetabular coverage affects capsular mechanics and joint stability in dysplastic hips. METHODS. Twelve cadaveric dysplastic hips (n = 12) were denuded to the capsule and mounted onto a robotic tester. The robot positioned each hip in multiple flexion angles (Extension, Neutral 0°, Flexion 30°, Flexion 60°, Flexion 90°) and performed internal-external rotations and abduction-adduction to 5 Nm in each rotational or planar direction. Each hip underwent a PAO, preserving the capsule, and was retested postoperatively in the robot. Paired sample t-tests compared the range of motion before and after PAO surgery (CI = 95%). RESULTS. Pre-operatively, the dysplastic hips demonstrated large ranges of internal-external rotations and abduction-adduction motions throughout all flexion positions. Post-operatively, the PAO slackenend the anterosuperior capsule and tightened the inferior capsule. This increased external rotation in Flexion 60° and Flexion 90° (∆. ER. = +16 and +23%) but provided lateral coverage to decrease internal rotation at Flexion 90° (∆. IR. = –15%). The PAO also reduced abduction throughout, but increased adduction in Neutral 0°, Flexion 30°, and Flexion 60° (∆. ADD. = +34, +30%, +29% respectively). CONCLUSIONS. The PAO provided crucial osseous structural coverage to the femoral head, decreasing hypermobility and adverse loading at extreme hip flexion-extension. However, it also slackened the anterosuperior capsule and increased adduction and external rotation, which may lead to ischiofemoral impingement and adductor irritations. Capsular instability may be secondary to acetabular undercoverage, thus capsular alteration may be warranted for larger corrections or rotational osteotomies. To preserve native hip and delay joint degeneration, it is crucial to preserve capsule and elucidate amount of reorientation needed without causing iatrogenic instability. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction. Bernese periacetabular osteotomy (PAO) repositions the acetabulum to increase femoral head coverage (FHC) in hip dysplasia. Currently, there is a paucity of objective peri-operative metrics to plan for optimal acetabular fragment repositioning. The MSk Lab Hip 3D Planner (MSkL-HP) measures acetabular morphology and simulates PAO cuts to achieve optimal FHC. We evaluated how adjusting location and orientation of cutting planes can alter FHC. Method. MSkL-HP simulated 274 feasible PAOs on four dysplastic hips. Femoroacetabular anatomy was landmarked to simulate cutting planes. Posterior column and ischial cuts were standardised, whilst iliac and pubic cut combinations varied. The slope of the iliac cut was either neutral (aligned to pelvis), exit point 5mm above the entry point (+5), or 5mm below (-5). The slope of the pubic cut was either 90°, 50°, or 70° (medial-to-lateral). Iliac and pubic cuts were simulated 0, 5 and 15mm - distal and medial – to a classic cut. Outcome measures were achieved LCEA, Tönnis, FHC and % bone overlap at the pubic cut. Targets were LCEA >30°, Tönnis angle <10°, and FHC >70% and minimum bone overlap ≥10%. Results. All feasible PAOs resulted in improvement from pre-operative metrics. Personalised cutting planes provided greater benefit than standard planes. Kruskal Wallis tests showed that the iliac cut at 5mm or 15mm resulted in a greater LCEA and lower Tönnis compared to the classic cut (p<0.05). Changing location of the pubic cut, and slope of the iliac and pubic cuts did not significantly affect LCEA and Tönnis in all hips (p<0.05). Cut combinations optimising metrics were associated with a lower % pubic cut overlap. Conclusion. MSkL-HP feasibly and reliably planned personalised PAO, measuring pre-operative and simulated post-operative objective metrics. Patient-specific pubic and iliac cuts enable greater correction whilst maintaining bone overlap. Further simulations on patients with varying morphology may improve standard techniques

Introduction. Progressive resistance training (PRT) as a mean to reduce symptoms in patients with hip dysplasia (HD) has not yet been tried out. The aim of this study was to examine if PRT is feasible in patients with HD. A secondary purpose was to report data on changes of patient reported outcomes, muscle performance and hip muscle strength following PRT. Materials and methods. Patients diagnosed with HD on the waiting list for a periacetabular osteotomy (PAO) were offered to participate in a PRT feasibility study. The PRT intervention consisted of 8-weeks of supervised PRT consisting of 20 training sessions with exercises for the hips and knees. Feasibility was evaluated as adherence, the number of dropouts and adverse events. Furthermore, pain was reported after each exercise and one day after a training session using a 100mm visual analog scale (VAS). Pain was categorized as “safe” (VAS ≤20), “acceptable” (VAS >20–50) and “high risk” (VAS >50). Pre- and post the intervention patients completed the Copenhagen Hip and Groin Outcome Score (HAGOS), performed two hop-tests on each leg and had their peak torque of the hip extensors and flexors assessed by isokinetic dynamometry. Results. 16 patients, mean age 28 (range 22–40) years, completed the PRT intervention. Adherence was high (90.3% ±9.0%). Acceptable pain levels (VAS ≤50) were reported on average of 95% during the completed PRT sessions and after 92.3% of the sessions when assessed on the following day. Four out of six HAGOS subscales improved (P <0.05) after the intervention, as did standing distance jump and countermovement jump (8.3 cm 95% CI [1.2, 15.3], 1.8 cm [0.7, 2.9]) on the affected side. Dynamometry showed significant improved peak torque during isokinetic concentric hip flexion (15.8 Nm 95% CI [5.9, 25.8]) on the affected side. A similar improvement was seen during isometric hip flexion on the non-affected side. Conclusion. Supervised preoperative PRT is feasible in terms of drop outs, adherence, adverse events and pain levels in patients with HD scheduled for PAO. Furthermore, this feasibility study suggests that PRT may improve pain levels, patient reported outcomes, functional performance and hip flexion muscle strength

Several experimental models have been used to produce intravascular fat embolism. We have developed a simple technique to induce fat embolism using corn oil emulsified with distilled water to form fatty micelles. Fat embolism was produced by intravenous administration of these fatty micelles in anaesthetised rats, causing alveolar oedema, haemorrhage and increased lung weight.

Histopathological examination revealed fatty droplets and fibrin thrombi in the lung, kidney and brain. The arteriolar lumen was filled with fatty deposits. Following fat embolism, hypoxia and hypercapnia occurred. The plasma phospholipase A₂, nitrate/nitrite, methylguidanidine and proinflammatory cytokines were significantly increased. Mass spectrometry showed that the main ingredient of corn oil was oleic acid.

This simple technique may be applied as a new animal model for the investigation of the mechanisms involved in the fat embolism syndrome.