Introduction
During the first peak of the pandemic, the NHS stopped non-urgent care and all resources were diverted to perform life or limb saving surgery. As the first peak of the pandemic passed, the challenge shifted towards safe resumption of elective orthopaedic surgery. Covid delays resulted in long waiting list delays. New protocols including preoperative self isolation, COVID-19 testing and surgery at ‘COVID-light’ or ‘green’ site were introduced to minimize the risk of viral transmission.

Materials and methods
This is a prospective single centre study of 100 patients who underwent elective hip and knee procedure between mid June 2020 to mid August 2020. Baseline characteristics of the patients and the rate of COVID infection were recorded. Furthermore, a COVID-modified satisfaction questionnaire was used to assess patient’s satisfaction.

Results

Mean patient age was 69.1 years (47-89 years). Mean length of hospital stay was 3 days(3-5 days). None of the patients contracted COVID19 and only one patient needed to be transferred over to the main hospital for further investigation. Only 3% were readmitted to the hospital after discharge. 70% of the patient completed a satisfaction questionnaire on their first follow up appointment 6 weeks after the surgery. All the patients were happy with the length of their hospital stay and scored a mean of 8.6 on a satisfaction scale (0-10).

Conclusion
The development of a COVID free pathway for elective orthopaedic patients resulted in great overall patient satisfaction, safe patient environment with zero COVID transmission.

Purpose: To investigate whether patient-specific factors and preoperative patient-reported outcome measures (PROMs) significantly predict 1-year WOMAC total score and EQ-5D-5L index of patients who underwent THA or TKA. Methods: A retrospective observational study. The clinic database was searched for patients who have undergone primary THA or TKA between January 2016 and December 2018. The inclusion criteria were met by 676 (373 THA) patients. Multiple regression models to estimate the contributions of nine different independent variables to the explanation of 1-year WOMAC total score or 1-year EQ-5D-5L health status index were carried out. Results: The mean age was 69.5 ± 10.3 years. Six predictors explained 21.4% (F (6, 669) = 30.9; p< 0.001) of the 1-year WOMAC score. Junger age (p= 0.006), higher preoperative EQ-5D-5L index (p= 0.004), lower patient clinical complexity level (PCCL) (p= 0.001), lower preoperative WOMAC score (p< 0.001), participation in a preoperative patient education (PPE) session (p= 0.004) and submitting for THA (p< 0.001) significantly predicted better 1-year WOMAC scores. Five factors were significant predictors of 1-year EQ-5D-5L index (F (5, 670) = 14.4; p< 0.001). Higher preoperative EQ-5D-5L index (p< 0.001), lower PCCL classification (p< 0.001), lower preoperative WOMAC score (p= 0.009), participation in a PPE session (p= 0.04) and submitting for THA (p= 0.01) were significant predictors of better 1-year EQ-5D-5L index. Conclusion: Better PROM scores preoperatively, less comorbidities, younger age, submitting for THA and attending a PPE session were predictors of better WOMAC total score and higher HRQoL 1-year after THA or TKA.

Introduction
Recent reports show that spinopelvic mobility influences outcome following total hip arthroplasty. This scoping review investigates the relationship between spinopelvic parameters (SPPs) and symptomatic femoroacetabular impingement (FAI).

Materials and Methods
A systematic search of EMBASE, PubMed and Cochrane for literature related to SPPs and FAI was undertaken as per PRISMA guidelines. Clinical outcome studies and prospective/retrospective studies investigating the role of SPPs in symptomatic FAI were included. Review articles, case reports and book chapters were excluded. Information extracted pertained to symptomatic cam deformities, pelvic tilt, acetabular version, biomechanics of
dynamic movements and radiological FAI signs.

Results
The search identified 42 papers for final analysis out of 1168 articles investigating the link between SPPs and pathological processes characteristic of FAI Only one (2 4%) study was of overcoverage parameters of FAI. In dynamic movements, decreased posterior pelvic tilt was a common feature in symptomatic FAI patients at increased hip flexion angles. FAI patients additionally demonstrated reduced sagittal pelvic ROM during dynamic hip flexion. Six studies found kinematic links between sagittal spinopelvic movement and sagittal and transverse plane hip movements.

Conclusions/Discussion
Our study shows that spinopelvic parameters can influence radiological and clinical manifestations of FAI, with pelvic incidence, acetabular version and muscular imbalances being aetiologically implicated. These factors may be amenable to non-surgical therapy. Individual spinopelvic mechanics may predispose to the development of FAI. If FAI pathoanatomy already exists, sagittal pelvic parameters can influence whether FAI symptoms develop and is an area of further research interest.

Introduction.
Femoral and tibial malrotations contribute to hip and knee joints kinematics. The treatment of femoral and tibial rotational deformities includes Proximal Femoral Derotation Osteotomy (PFDO) and Distal Tibial Derotation Osteotomy (DTDO), respectively. We aimed to determine the clinical effectiveness of these interventions in improving patients’ hip and knee symptoms.

Materials.
A review of patients that underwent DTDO (2018-2020). Pre-operative and interval post-operative functional outcomes were correlated. Functional outcomes included international hip outcome tool (iHOT12), hip and knee outcome score activities of daily living scale (HOS-ADLS and KOS-ADLS, respectively) and sport scale (HOS-SS and KOS-SS, respectively), non-arthritic hip score (NAHS) and anterior knee pain (AKP).

Results.
22 patients underwent PFDO (13–females; average age–24years (17-38)) and 30–DTDO (27–females: average age–27years (18-44)). Average follow-up–20months (2-35). Statistical difference between pre-operative and post-operative scores was achieved 18 and 12months for PFDO and DTDO, respectively.
Pre-operative vs 18months post-operative scores for PFDO: 33 vs 88 for iHOT12; 55 vs 91 for HOS-ADLS; 44 vs 86 for HOS-SS; 57 vs 89 for NAHS. Pre-operative vs 12months post-operative scores for DTDO: 38 vs 97 for iHOT12; 58 vs 94 for KOS-ADLS; 52 vs 96 for KOS-SS; 58 vs 94 for AKP.

Conclusions.
Femoral and tibial derotation osteotomies are effective interventions. Recovery is more rapid post-tibial osteotomy. Both osteotomies lead to a functional recovery to near-normal level.

Introduction.
Contribution of tibial malrotation to hip joint kinematics and impingement is poorly understood. Tibial malrotation treatment includes Distal Tibial Derotation Osteotomy (DTDO). We aimed to determine DTDO clinical effectiveness in patients with hip symptoms.

Materials.
A review of patients undergoing DTDO (2018-2020). We reviewed our management of tibial torsion and associated ipsilateral pathology: MRI-defined intra-articular pathomorphology (CAM/pincer) and non-CAM/pincer-related labral tears, as well as excessive combined femoral/acetabular version (McKibbin Index (MI) >50o). If presenting symptoms resolved, patients were discharged at 1year.

Results.
27 patients underwent DTDO for hip pain, 3 for hip and knee pain. Mean tibial torsion–48.6o (41-63o). Average age–27years (18-44), average follow-up–20months(3-36).
Thirteen patients (43%) had a co-existent CAM/pincer, 7 (23%) – excessive MI(51-76o).
Of 13 CAM/pincer patients post-DTDO:
• 2–settled (discharged)
• 4–hip arthroscopy pre-DTDO
o 1–settled post-DTDO (discharged)
o 3–persistently symptomatic <1yr follow-up, including 1 with excessive MI (51o)
• 3–persistent hip symptoms >1yr post-DTDO underwent and 1 awaits hip arthroscopy (all normal MI)
• 4–improving <1yr post-DTDO.
Of 17 non-CAM/pincer patients:
• 4 had labral tears
o 2–settled post-DTDO (discharged)
o 2–improving (<1yr follow-up)
• 7 had excessive MI
o 2–discharged
o 5–under review (<1yr follow-up)
• 6 others–discharged
• no direct hip interventions required to date.

Conclusion.
Patients with rotational malalignment frequently present with multi-level deformity and high prevalence of co-existent CAM/pincer. Hip arthroscopy for intra-articular pathology prior to malrotation correction is likely to fail. Malrotation correction should be prioritised. Significant proportion of symptomatic hip impingement patients improve post-DTDO.

Coxa saltans or snapping hip is a condition characterized by audible snaps that occur on provocative movements of the hip. It is prevalent in athletes who perform extreme range of motion of the hip. Iatrogenic trauma, anatomical variations or pathologies such as Ehlers-Danlos and femoral osteochondroma have been cited as precipitants. A distressed 27-year-old-female presented with painless, chronic clicking of the left hip since a sports accident 12-years prior. Active and passive hip movements were full with normal gait and no limb length discrepancy. Snapping is voluntarily reproducible with hip adduction and internal rotation. MRI of the left hip demonstrated irregularity and thickening of the ligamentum teres; suggestive of partial tear. After 4-months of isometric strengthening and stretching exercises, patient was satisfied by the reduced frequency of involuntary clicking. Classification is based on the implicated structures; external, internal or intra-articular. Female preponderance is explained by the increased hip-width-to-femoral-length that may generate greater strain on the hip abductors and iliotibial band (ITB). Increased distance between greater trochanters and narrow bi-iliac width with ITB tightness, shorter muscle or tendon lengths may be present. Radiological modalities of choice include dynamic ultrasound and MRI. Symptoms are often amenable to physiotherapy, analgesia and lifestyle modifications. Z-shaped ITB release, Z-lengthening, cross-shaped release, release of the gluteus maximus tendon insertion to the femur, and iliopsoas tendon lengthening or tenotomy; are described for external and internal causes. Debridement and arthroscopic repairs are indicated for intra-articular pathologies. In patients refractory to conservative measures, surgery is indicated for symptomatic relief.

Introduction.
Hip impingement can be caused by intra-articular pathology (CAM/pincer) and/or combined femoral/acetabular version abnormality. The latter is treated based on the severity of predominant component. Proximal Femoral (PF) malrotation treatment includes Proximal Femoral Derotation Osteotomy (PFDO). We aimed to determine PFDO clinical effectiveness in patients with hip symptoms.

Materials.
A review of patients undergoing PFDO (2018-2020). We reviewed our management of femoral torsion and associated MRI-defined intra-articular pathomorphology: CAM/pincerlabral tears and non-CAM/pincer-related labral tears. Combined femoral/acetabular version was assessed using McKibbin Index (MI) (normal ranges: MI–20-50o, acetabular version–10-25o, PF–10-25o). If presenting symptoms resolved, patients were discharged at 18months.

Results.
22 patients underwent PFDO for hip pain. Average age–24years (17-38), average follow-up–20months (3-36).

Observed prevalence of version abnormalities in our cohort were:
• MI
o 8–Excessive retroversion (range -5–5o,median–3o),
o 14–Excessive anteversion (51–67o,median–55o);
• Acetabulum
o 11–Relative retroversion (-2–9o,median–4o),
o 11–Normal (11–23o,median–19o);
• PF
o 8–Relative retroversion (-8–5o,median–0o),
o 14–Excessive anteversion (26–54o,median–34o).

Overall, 12 patients settled post-PFDO and were discharged at 18months follow-up.

Of 10 patients with associated MRI-defined CAM/pincer pathomorphology
• 4 had hip arthroscopy prior to PFDO (discharged)
• 1 required hip arthroscopy post-PFDO
• 5 – no hip arthroscopy required (2–discharged, 3– <18months follow-up).

Conclusion.
Patients with hip impingement present with high prevalence of rotational malalignment. Hip arthroscopy for intra-articular pathology prior to malrotation correction is likely to fail. Primary correction of malrotation is crucial and leads to symptom resolution in significant proportion of patients.

Purpose: This article aims to systematically summarise literature regarding heterotopic ossification after hip arthroscopy, with focus on risk factors, incidence, disease distribution as per Brooker’s classification and efficacy of prophylactic measures. Methods: This scoping review adheres to the methodological frameworks of Arksey, Levac and Peters. A computer-based search was performed in PubMed, Embase, Emcare, Cinahl, ISI web of science and Scopus. Articles reporting the incidence of heterotopic ossification following hip arthroscopy were included after title/abstract and full-text screening, performed independently by two reviewers. Results: Of the 664 articles retrieved, 45 studies involving 12,709 hips were included. The proportion of patients with heterotopic ossification ranged from 0%-44%, with a pooled incidence of 4.4%. The majority of cases (91.7%) were Brooker grade I or II. Of the six studies investigating nonsteroidal anti-inflammatory drug (NSAID) prophylaxis, five reported a significantly lower incidence of heterotopic ossification with its use. Some evidence suggests that capsular closure, patient sex and degree or type of resection may affect the development of heterotopic ossification. Discussion: Evidence exists advocating the administration of post-operative NSAIDs in order to reduce the incidence of heterotopic ossification following hip arthroscopy. However, given that the majority of cases are asymptomatic Brooker grade I or II presentations, with limited influence on post-operative outcomes, the use of NSAID prophylaxis must be balanced against the risks. The identification of risk factors associated with the development of heterotopic ossification may allow clinicians to risk stratify patients, aiding in patient selection and decision making with respect to NSAID prophylaxis.

Background: Research surrounding the optimum number of screws to stabilise PAO is limited. Objective: To determine if there is a difference in stability when comparing 2 versus 3 or more (3+) screws in acetabular fragment fixation. Methods: A retrospective clinical and radiological review of 243 hips (68.7% primary DDH diagnosis) split into two patient groups: Group 1: 61 PAOs (36.1% L sided) fixed with 2 screws (75.4% female, mean age 27.3+/-12.2 years, mean BMI 23.6+/-4.2); Group 2: 182 PAOs (45.6% L sided) fixed with 3+ screws (74.2% female, mean age 26.0+/-12.2 years, mean BMI 25.2+/-5.2). The study group included patients treated between September 2006 to May 2020 across two hospitals under one surgeon. Radiological parameters were assessed pre-operatively and followed-up for 61.0+/-17.7 months (Group 1) and 64.3+/-34.5 months (Group 2) post-operatively. Results: There was significant difference in inferior pubic-ramus stress fractures: 13.1% (Group 1) and 4.4% (Group 2) (p=0.032), and in superior pubic-ramus non-union: 16.4% (Group 1) and 6.6% (Group 2) (p=0.021). There was no significant difference in posterior column stress fractures: 0.0% (Group 1) and 1.6% (Group 2), in posterior column non-unions: 1.6% (Group 1) and 2.2% (Group 2) and in broken screws: 6.6% (Group 1) and 3.3% (Group 2). Acetabular migration was also significantly different at 6.6% (Group 1) and 0.5% (Group 2) (p=0.015). Two of the 5 patients who suffered from acetabular migration were later revised (both of which were in Group 1). Conclusion: Stability is increased when using 3+ screws in fixation, compared to 2 screws.

INTRODUCTION: Symptomatic hip osteonecrosis related to sickle cell disease (SCD) has a high risk of progression to collapse and total hip arthroplasty (THA) in this disease has a high rate of complications. We asked question about the benefit of performing an IRM to detect and treat with cell therapy an early (stage I or II) contralateral osteonecrosis when a THA is performed for late stage (collapse) on the other side. METHODS: 430 consecutive SCD (32 years, 18-51) patients with bilateral symptomatic hip osteonecrosis had one side with collapse treated with THA and the contralateral without collapse (stage I or II) treated with cell therapy (160,000 ± 45,000 MSCs). RESULTS: At the most recent FU (average 20 years, 10-30 years), with cell therapy treatment, 45 hips (10.5%) had collapsed and had required THA while 380 hips (88%) were without collapse and asymptomatic (or with few symptoms). Among the 430 contralateral hips treated with a primary THA, 96 (22.3%) had required one revision, 28 of these 96 hips had a re-revision, and 12 of 28 had required a third re-revision for loosening (85%) or infection (6%). Hips undergoing cell therapy were approximately three times less likely to undergo revision or re-revision surgery (p < 0.01) as compared with hips undergoing a primary THA. CONCLUSION: When arthroplasty for osteonecrosis is planned in sickle cell disease, it is worth performing cell therapy on early-stage contralateral osteonecrosis during the same anesthesia.

Introduction: Hip fracture, a major public health problem, causes functional decline in patients. Many factors that influence recovery after hip fracture surgery are non-modifiable. Vitamin D deficiency, a potentially modifiable risk factor, is prevalent in hip fracture patients and associated with increased mortality and complications. This study aims to assess possible associations between vitamin D levels on admission and 6-month functional outcome after hip fracture surgery. Methods: Patients with hip fracture surgery from 2012 to 2016 were identified. Retrospective analysis was performed on clinical parameters including age, gender, vitamin D, anaemia, comorbidities, and type of surgery. Patients were stratified along four vitamin D levels – severe deficiency (≤10ng/mL), mild deficiency (10-20ng/ml), insufficiency (20-30ng/ml) and normal (>30ng/ml). Functional outcome measured were Harris Hip Score, Parker Mobility Score (PMS) and individual domains of 36-Item Short Form Health Survey (SF36). Univariate and multivariate analyses were conducted to examine the association between vitamin D levels and functional outcome. Results: Of 664 patients with mean age of 77 years, 9% had severe vitamin D deficiency and 39% mild deficiency. 71% were female. 55% received joint-replacing procedures and the rest joint-preserving (fixation) procedures. Patients with severe vitamin D deficiency had significantly poorer baseline and 6-month PMS and SF36 Physical Functioning (PF). Multivariate analysis demonstrated lower 6-month PMS and SF36 PF in severe vitamin D deficient patients after accounting for baseline scores and other factors. Conclusion: Severe vitamin D deficiency is an independent risk factor for poorer functional recovery and quality of life after hip fracture surgery.