A new minimally invasive transsartorial approach for periacetabular osteotomy

The Impact of Epidural Analgesia on Immobility and extended Hospital Stay After Periacetabular Osteotomy

AIMS

Early mobilisation after periacetabular osteotomy (PAO) represents an important goal after surgery. The purpose of this study was to determine whether the use of epidural aznalgesia (EA) is associated with prolonged immobility and an increased length of stay (LOS) after PAO surgery.

METHODS

From January 2022 to July 2023, the study included a cohort of 150 PAO procedures all performed by the same surgeon (SSA). Patients were categorized into two distinct groups: those who received epidural analgesia (EA) (79 PAOs) and those who did not receive EA (71 PAOs). "Ready for discharge" was defined as the ability to ascend and descend a standardized flight of stairs independently. Multivariable linear regression was used to identify additional factors influencing LOS after PAO.

RESULTS

Patients in the EA group were ready for discharge 5.95 ± 2.09 days after surgery which was significantly longer than in the No EA group´s average of 4.18 days ± 2.5, (p < 0.001). While the reduction in the number of patients experiencing pulmonary embolism in the No EA group did not reach statistical significance, it still demonstrated a relevant decrease from two patients within the EA group (2.53%) to 0 (0%) in the No EA group. The active engagement of the surgeon in mobilising patients led to a substantial reduction in LOS, decreasing it from 5.81 ± 2.18 days to 2.2 ± 0.77 days (p < 0.001). Multivariable analysis revealed five independent factors influencing the LOS following PAO which included absence of EA, surgeon-led mobilisation within 24 h after surgery, postoperative hemoglobin levels, BMI, and prior experience with PAO surgery on the contralateral side.

CONCLUSIONS

Opting against the use of EA in patients undergoing PAO is advisable, as it will result in extended postoperative immobility and the associated risks. Additionally, the active participation of the surgeon in the mobilisation process is strongly recommended.

Functional and radiological outcomes of periacetabular osteotomy for hip dysplasia in patients under fifty years using a minimally invasive approach-a single surgeon series with a minimum follow up of two years

PURPOSE

We conducted a retrospective analysis of prospectively collected data to evaluate (1) the extent of surgical correction following minimally invasive periacetabular osteotomy, (2) improvements in functional outcomes and any potential predictors for favourable outcome, and (3) complications after minimally invasive periacetabular osteotomy.

METHODS

A total of 352 minimally invasive periacetabular osteotomy procedures were performed on 312 hip dysplasia patients between 2013 and 2020. Radiological parameters such as lateral centre edge angle, acetabular index, and Tönnis grade of arthritis were calculated. Patients also completed a range of patient reported outcome measures. Wilcoxon signed-rank tests were performed to assess for differences between patient reported outcome measures and radiological outcomes across the follow-up periods. Univariate linear regression and logistic regression were used to assess for predictors of change in functional outcome.

RESULTS

Patients had a significant correction in mean lateral centre edge angle from 17.2° to 35.3° (p < 0.001) and mean acetabular index from 13.2° to - 0.82°. At one year follow-up all patient reported outcome measures were significantly greater than their baseline measurements and this improvement was maintained at two years. Changes in patient reported outcome measures were independent of radiological parameters such as change in the lateral centre edge angle and acetabular index, pre-operative Tönnis grade, and patient factors such as age and sex. A total of 5.11% of patients developed post-operative complications, with four requiring posterior column fixation. Four patients (1.12%) needed a total hip replacement.

CONCLUSION

Minimally invasive periacetabular osteotomy is a safe procedure that provides significant functional outcome improvements following surgery at six months which is maintained at two years. More than three-fourths of patients achieved improvement of iHOT-12 score beyond the minimal clinically important difference and more than half of the patients achieved substantial clinical benefit for iHOT-12 score.

Step-cut osteotomy of the anterior superior iliac spine for increased visualisation in the Levine approach for Bernese periacetabular osteotomy surgery

BACKGROUND

Hip dysplasia can lead to pain and dysfunction in the young adult. Acetabular undercoverage leads to abnormal joint loading and results in joint degeneration, accelerating need for arthroplasty in this patient population. Conceptually, treatment focuses on increasing acetabular coverage in the form of periacetabular osteotomy. The procedure can be performed through the iliofemoral approach, and performing an anterior superior iliac spine (ASIS) osteotomy can enhance the visualisation in this approach. Several techniques have been described for ASIS osteotomy.

AIM

The purpose this study was to report on step-cut technique for ASIS osteotomy during the Bernese periacetabular osteotomy procedure to enhance visualisation when utilising the iliofemoral approach.

SURGICAL TECHNIQUE

This step-cut technique enhances stability at the osteotomy site, and minimises soft tissue dissection to reduce pain and assists with maintaining a stable fixation construct postoperatively.

RESULTS

There were no nonunions and minimal morbidity to the lateral femoral cutaneous nerve injury in cohort of 86 patients while utilising this technique.

CONCLUSIONS

We recommend using this step-cut ostetomy of the ASIS during Bernese periactetabular osteotomy for benefit of increasing exposure while maintaining a low complication profile.

Is the Femoral-Epiphyseal Acetabular Roof (FEAR) index associated with hip pain in patients with hip dysplasia?

BACKGROUND

Micro instability of the hip joint has been suggested to cause pain in patients with hip dysplasia. Recently, the Femoral-Epiphyseal Acetabular Roof (FEAR) index has been developed to evaluate hip instability in patients with dysplasia.

PURPOSE

To investigate associations between the FEAR index and patient-reported outcomes before and six months after periacetabular osteotomy (PAO).

MATERIAL AND METHODS

Radiographs of patients with hip dysplasia who underwent PAO between 2018 and 2020 were retrospectively assessed by a radiologist and an orthopedic surgeon. Radiographic measurements indicative of hip instability (Shenton's line, FEAR index, center-edge angle of Wiberg, acetabular index of Tönnis, and the femoral neck-shaft angle) were measured. Data on hip pain, function, and quality of life were collected prospectively using the Hip dysfunction and Osteoarthritis Outcome Score (HOOS).

RESULTS

A total of 222 patients were included in the study. All radiographic measurements and patient-reported outcomes improved significantly from preoperative to six months postoperative (P < 0.001). There were no differences in the change score of patient-reported outcomes between patients with a FEAR index >2° (indicative of hip instability) and patients with a FEAR index ≤2°.

CONCLUSION

The FEAR index was not associated with hip pain, function, and quality of life among patients with hip dysplasia. This study did not find evidence supporting that instability defined by the FEAR index caused pain in patients with hip dysplasia.

Driving reaction time following periacetabular osteotomy

INTRODUCTION

Periacetabular osteotomy (PAO) is increasingly being used to treat young adults with symptomatic hip dysplasia. Currently there is a lack of evidence to guide return to driving after this procedure. This study aimed to identify the length of time required after a Periacetabular Osteotomy procedure before a patient can safely return to driving.

METHODS

All patients undergoing PAO were assessed for suitability for the study. Inclusion criteria were: currently driving with a valid licence; and being able to attend follow-up assessment. Baseline driving reaction time was assessed using a driving simulator preoperatively. The simulation was repeated 5 times for each patient and reaction times recorded (Thinking time, Action time and Total reaction time for braking at 30 mph). The driving simulation was repeated using the same methods at 6 weeks and 12 weeks postoperatively. Pre- and postoperative times were compared.

RESULTS

26 patients were included (24 females, 2 males) with a mean age of 32 (range 19-50) years. The mean preoperative times were: Thinking time 0.48, Action time 0.21, Total time 0.69 seconds. At 6 weeks postoperatively, mean Action time increased to 0.26 seconds (p = 0.012) and mean Total time increased to 0.78 seconds (p = 0.013). By 12 weeks post procedure, there was no significant difference in reaction times compared to baseline (mean Thinking time 0.47 seconds, Action time 0.23, Total time 0.72; p > 0.05).

CONCLUSIONS

Most patients may not be safe to drive at 6 weeks following PAO procedures but should be safe to drive at 12 weeks postoperatively. Individual patient factors should also be taken into consideration.

Feasibility and acceptability of a six-month exercise and patient education intervention for patients with hip dysplasia: A mixed methods study

BACKGROUND AND OBJECTIVES

To evaluate the feasibility and acceptability of exercise and patient education for patients with hip dysplasia not receiving surgery.

DESIGN

Feasibility study.

METHODS

The participants received exercise instruction and patient education over six months. Feasibility covered recruitment, retention, and mechanisms of change (MC). MC were measured with Hip and Groin Outcome Score (HAGOS), muscle strength tests, Y-balance test, and hop for distance test (HDT) over six months. Acceptability covered adherence, expectations, perceptions, benefits, and harms.

RESULTS

Thirty of 32 were recruited (median age: 30 years); six were lost to follow-up. Twenty-four participants improved by a mean of 11 (95%CI: 5-17) HAGOS pain points, improvements in all subscales were 1-11 points. Mean hip abduction strength improved 0.2 (95%CI: 0.04-0.4) Nm/kg, similar to flexion and extension. Median Y-balance test improvements: anterior: 70 (IQR: 64-74) to 75 (IQR: 72-80) centimetres; posteromedial: 104 (IQR: 94-112) to 119 (IQR: 112-122) centimetres and posterolateral: 98 (IQR: 89-109) to 116 (IQR: 108-121) centimetres (p < .001). Median improvement in HDT was: 37 (IQR: 30-44) to 52 (IQR: 45-58) centimetres (p < .001). Participants adhered to 84% of scheduled sessions (1,581:1,872), expectations were met, and perceptions were characterized by high self-efficacy for exercise. Benefits were reported with no serious harms.

CONCLUSION

Patients with hip dysplasia are willing to be recruited for exercise and patient education, with acceptable retention. MC were observed through improvements in pain, strength and function with high acceptance of the exercise and patient education intervention. Thus, it seems feasible to conduct a full-scale randomised controlled trial.

Physical impairments in Adults with Developmental Dysplasia of the Hip (DDH) undergoing Periacetabular osteotomy (PAO): A Systematic Review and Meta-Analysis

Background

Developmental dysplasia of the hip (DDH) is a condition associated with hip pain and impairments. Periacetabular osteotomy (PAO) is a common surgical treatment for DDH. Outcomes following PAO have historically been based on radiology or patient reported outcomes, and not physical impairments.

Objective

To investigate differences in physical impairments in adults with DDH undergoing PAO compared with asymptomatic participants, and to investigate pre- to post-PAO changes in physical impairments.

Design

Systematic review with meta-analysis.

Methods

A literature search was performed in five databases (MEDLINE, CINAHL, EMBASE, Sports Discuss, and PsychINFO), using the PRISMA checklist. Studies were considered eligible if patients were aged 15 years and older, treated with PAO for DDH and if they included a physical impairment outcome measure. Two independent reviewers performed data extraction and assessed methodological quality, using a modified version of the Downs and Black checklist.

Results

Of 5,017 studies, 24 studies were included with 2190 patients. The methodological quality scores ranged from 39% to 88%. With low level of evidence, meta-analysis showed 58% of patients had a positive anterior impingement test (95%CI: 39-76%), prior to PAO and one to three years after PAO. Five years after PAO, the proportion fell to 17% (95%CI: 11-24%). Prior to PAO, patients with DDH walked with a lower peak hip extension angle, compared to asymptomatic participants (SMD 0.65 (95%CI 0.21-1.10). Best evidence synthesis of non-pooled data showed limited evidence of increased walking velocity, stride length and improved hip flexion and extension moment 18-months post-PAO compared to pre-op. Cadence, hip abduction and hip flexion strength did not change.

Conclusion

Most patients with DDH have a positive hip impingement test, pre-PAO. Compared to asymptomatic participants, patients with DDH demonstrate physical impairments during walking which appear to improve after surgery. Hip abduction and flexion strength did not change pre- to post-PAO.

Level of Evidence

1b.

Comparing exercise and patient education with usual care in the treatment of hip dysplasia: a protocol for a randomised controlled trial with 6-month follow-up (MovetheHip trial)

INTRODUCTION

Surgery is not a viable treatment for all patients with hip dysplasia. Currently, usual care for these patients is limited to a consultation on self-management. We have shown that an exercise and patient education intervention is a feasible and acceptable intervention for patients not receiving surgery. Therefore, we aim to investigate whether patients with hip dysplasia randomised to exercise and patient education have a different mean change in self-reported pain compared with those randomised to usual care over 6 months. Furthermore, we aim to evaluate the cost-effectiveness and perform a process evaluation.

METHODS AND ANALYSIS

In a randomised controlled trial, 200 young and middle-aged patients will be randomised to either exercise and patient education or usual care at a 1:1 ratio through permuted block randomisation. The intervention group will receive exercise instruction and patient education over 6 months. The usual care group will receive one consultation on self-management of hip symptoms. The primary outcome is the self-reported mean change in the pain subscale of the Copenhagen Hip and Groin Outcome Score (HAGOS). Secondary outcomes include mean changes in the other HAGOS subscales, in the Short Version of the International Hip Outcome Tool, in performance, balance and maximal hip muscle strength. Between-group comparison from baseline to 6-month follow-up will be made with intention-to-treat analyses with a mixed-effects model. Cost-effectiveness will be evaluated by relating quality-adjusted life years and differences in HAGOS pain to differences in costs over 12 months. The functioning of the intervention will be evaluated as implementation, mechanisms of change and contextual factors.

ETHICS AND DISSEMINATION

The study protocol was approved by the Committee on Health Research Ethics in the Central Denmark Region and registered at ClinicalTrials. Positive, negative and inconclusive findings will be disseminated through international peer-reviewed scientific journals and international conferences.

TRIAL REGISTRATION NUMBER

NCT04795843.

Transversus Abdominis Plane Block Reduces Intraoperative Opioid Consumption in Patients Undergoing Periacetabular Osteotomy

Background: Administering intraoperative analgesia in patients undergoing periacetabular osteotomy (PAO) is challenging due to both the relevant surgical approach and osteotomies, which are associated with pain. The aim of this study was to assess the effect of the transversus abdominis plane block (TAPb) on intraoperative opioid consumption and circulation parameters in PAO patients. Patients and Methods: We conducted a two-group randomized-controlled trial involving 42 consecutive patients undergoing PAO for symptomatic developmental dysplasia of the hip (DDH) in our department. Patients assigned to the study group received an ultrasound-guided TAPb with 0.75% ropivacaine before the beginning of the surgery and after general anesthesia induction. Patients assigned to the control group did not receive a TAPb. General anesthesia was conducted according to a defined study protocol. The primary endpoint of the study was the intraoperative opioid consumption, measured in morphine equivalent dose (MED). Secondary endpoints were the assessment of intraoperative heart rate, mean arterial pressure (MAP), need for hypotension treatment, and length of hospital stay (LOHS). A total of 41 patients (n = 21 TAPb group, n = 20 control group) completed the study; of these, 33 were women (88.5%) and 8 were men (19.5%). The mean age at the time of surgery was 28 years (18–43, SD ± 7.4). All operations were performed by a single high-volume surgeon and all TAPb procedures were performed by a single experienced senior anesthesiologist. Results: We observed a significantly lower intraoperative opioid consumption in the TAPb group compared to the control group (930 vs. 1186 MED per kg bodyweight; p = 0.016). No significant differences were observed in the secondary outcome parameters. We observed no perioperative complications. Conclusion: Ultrasound-guided TAPb significantly reduces intraoperative opioid consumption in patients undergoing PAO.

Periacetabular osteotomy: A novel application of modified Stoppa approach

Background: The Bernese periacetabular osteotomy (PAO) is a well-established procedure for symptomatic hip dysplasia in adolescents and young adults. However, it remains a technically demanding procedure, and several major complications have been described, many of which are related to the approach and surgical exposure. The current study evaluates the efficacy and safety of PAO performed through a modified Stoppa approach. Methods: A prospective series of nine consecutive patients with hip dysplasia were treated PAO through the modified Stoppa approach. The mean age was 22.4 years (15–30 years) and the mean follow-up was 3.2 years (2–5 years). Harris hip score (HHS) was used as a functional score, and the radiographic indices included the lateral center-edge angle (LCEA) and Tönnis roof angle. Results: The approach allowed the osteotomy lines to be performed under direct visualization from the intra-pelvic surface of the acetabulum, aided by fluoroscopy. A lateral window was added to perform the final iliac cut and for subsequent mobilization and fixation of the acetabular fragment. The mean HHS improved significantly from 70.8 ± 4.9 points to 90.1 ± 3.3 points (p < 0.001). The mean LCEA improved from 8.2° ± 4.9 (range: 0–14) to 32.7° ± 5.3 (range: 26–40), with a mean improvement of 24.5°. The mean Tönnis angle improved from 28.4° ± 4.4 (range: 22–35) to 3.8° ± 3.3 (range: 0–10). Two patients had irritation from prominent screw heads that necessitated removal 1 year after the index procedure. One patient had radiographic progression of osteoarthritis. No cases of infection, non-union, heterotopic ossification, or nerve palsy were identified till the latest follow-up. Conclusion: Ganz PAO can be safely conducted through the modified Stoppa approach, providing direct exposure to the osteotomized surfaces, and protecting susceptible neuro-vascular structures.

Level of evidence: IV.

Capsular Mechanics After Periacetabular Osteotomy for Hip Dysplasia

BACKGROUND

Hip dysplasia is characterized by insufficient acetabular coverage around the femoral head, which leads to instability, pain, and injury. Periacetabular osteotomy (PAO) aims to restore acetabular coverage and function, but its effects on capsular mechanics and joint stability are still unclear. The purpose of this study was to examine the effects of PAO on capsular mechanics and joint range of motion in dysplastic hips.

METHODS

Twelve cadaveric dysplastic hips (denuded to bone and capsule) were mounted onto a robotic tester and tested in multiple positions: (1) full extension, (2) neutral 0°, (3) flexion of 30°, (4) flexion of 60°, and (5) flexion of 90°. In each position, the hips underwent internal and external rotation, abduction, and adduction using 5 Nm of torque. Each hip then underwent PAO to reorient the acetabular fragment, preserving the capsular ligaments, and was retested.

RESULTS

The PAO reduced internal rotation in flexion of 90° (∆IR = -5°; p = 0.003), and increased external rotation in flexion of 60° (∆ER = +7°; p = 0.001) and flexion of 90° (∆ER = +11°; p = 0.001). The PAO also reduced abduction in extension (∆ABD = -10°; p = 0.002), neutral 0° (∆ABD = -7°; p = 0.001), and flexion of 30° (∆ABD = -8°; p = 0.001), but increased adduction in neutral 0° (∆ADD = +9°; p = 0.001), flexion of 30° (∆ADD = +11°; p = 0.002), and flexion of 60° (∆ADD = +11°; p = 0.003).

CONCLUSIONS

PAO caused reductions in hip abduction and internal rotation but greater increases in hip adduction and external rotation. The osseous acetabular structure and capsule both play a role in the balance between joint mobility and stability after PAO.

[Minimally invasive periacetabular osteotomy for adult hip dysplasia]

OBJECTIVE

Performance of a periacetabular osteotomy (PAO) using a minimally invasive approach for three-dimensional correction of the acetabular position.

INDICATIONS

Symptomatic developmental dysplasia of the hip in adolescents and adults.

CONTRAINDICATIONS

Advanced osteoarthritis of the hip, incongruence of the hip joint surfaces.

SURGICAL TECHNIQUE

A periacetabular osteotomy is performed via a minimally invasive approach.

RESULTS

In total, 39 patients were followed up for 3.5 (3-4.5) years. The lateral center-edge angle of Wiberg increased significantly from 16.1° (7-24°) to 30.5° (25-37°) (p < 0.0001), the acetabular index changed from 13.2° (2-25.3°) to 2.8° (-3-13°; p < 0.0001). Mean duration of surgery was 88 (57-142) minutes. No major complications occurred.

Effect of coronal plane acetabular correction on joint contact pressure in Periacetabular osteotomy: a finite-element analysis

Background

The ideal acetabular position for optimizing hip joint biomechanics in periacetabular osteotomy (PAO) remains unclear. We aimed to determine the relationship between acetabular correction in the coronal plane and joint contact pressure (CP) and identify morphological factors associated with residual abnormal CP after correction.

Methods

Using CT images from 44 patients with hip dysplasia, we performed three patterns of virtual PAOs on patient-specific 3D hip models; the acetabulum was rotated laterally to the lateral center-edge angles (LCEA) of 30°, 35°, and 40°. Finite-element analysis was used to calculate the CP of the acetabular cartilage during a single-leg stance.

Results

Coronal correction to the LCEA of 30° decreased the median maximum CP 0.5-fold compared to preoperatively (p <  0.001). Additional correction to the LCEA of 40° further decreased CP in 15 hips (34%) but conversely increased CP in 29 hips (66%). The increase in CP was associated with greater preoperative extrusion index (p = 0.030) and roundness index (p = 0.038). Overall, virtual PAO failed to normalize CP in 11 hips (25%), and a small anterior wall index (p = 0.049) and a large roundness index (p = 0.003) were associated with residual abnormal CP.

Conclusions

The degree of acetabular correction in the coronal plane where CP is minimized varied among patients. Coronal plane correction alone failed to normalize CP in 25% of patients in this study. In patients with an anterior acetabular deficiency (anterior wall index < 0.21) and an aspherical femoral head (roundness index > 53.2%), coronal plane correction alone may not normalize CP. Further studies are needed to clarify the effectiveness of multiplanar correction, including in the sagittal and axial planes, in optimizing the hip joint’s contact mechanics.

Highly Cited Articles in Periacetabular Osteotomy Research

Purpose

The aim of this study is to identify highly cited articles and examine trends and characteristics in research on periacetabular osteotomy.

Materials and Methods

The 50 most highly cited articles on periacetabular osteotomy research were identified using Scopus. Data regarding article demographics and publication were collected from each article and an analysis was performed.

Results

The mean citation count was 125±37. The article with the highest total citation count (796), five-year citation count (327), and five-year citation density (65/year) was reported by Reinhold Ganz. The five-year citation density showed strong correlation with total citation density (r=0.930, P<0.001). Reinhold Ganz, the most productive author, was listed on 13 articles in the cohort with 455 weighted citation points.

Conclusion

This study provides a collection of articles examining periacetabular osteotomies and demonstrates that citation count can be regarded as an acceptable measure of the contemporary academic influence of an article.

Is Anterior Rotation of the Acetabulum Necessary to Normalize Joint Contact Pressure in Periacetabular Osteotomy? A Finite-element Analysis Study

BACKGROUND

Inappropriate sagittal plane correction can result in an increased risk of osteoarthritis progression after periacetabular osteotomy (PAO). Individual and postural variations in sagittal pelvic tilt, along with acetabular deformity, affect joint contact mechanics in dysplastic hips and may impact the direction and degree of acetabular correction. Finite-element analyses that account for physiologic pelvic tilt may provide valuable insight into the effect of PAO on the contact mechanics of dysplastic hips, which may lead to improved acetabular correction during PAO.

QUESTIONS/PURPOSES

We performed virtual PAO using finite-element models with reference to the standing pelvic position to clarify (1) whether lateral rotation of the acetabulum normalizes the joint contact pressure, (2) risk factors for abnormal contact pressure after lateral rotation of the acetabulum, and (3) whether additional anterior rotation of the acetabulum further reduces contact pressure.

METHODS

Between 2016 and 2020, 85 patients (92 hips) underwent PAO to treat hip dysplasia. Eighty-two patients with hip dysplasia (lateral center-edge angle < 20°) were included. Patients with advanced osteoarthritis, femoral head deformity, prior hip or spine surgery, or poor-quality images were excluded. Thirty-eight patients (38 hips) were eligible to participate in this study. All patients were women, with a mean age of 39 ± 10 years. Thirty-three women volunteers without a history of hip disease were reviewed as control participants. Individuals with a lateral center-edge angle < 25° or poor-quality images were excluded. Sixteen individuals (16 hips) with a mean age of 36 ± 7 years were eligible as controls. Using CT images, we developed patient-specific three-dimensional surface hip models with the standing pelvic position as a reference. The loading scenario was based on single-leg stance. Four patterns of virtual PAO were performed in the models. First, the acetabular fragment was rotated laterally in the coronal plane so that the lateral center-edge angle was 30°; then, anterior rotation in the sagittal plane was added by 0°, 5°, 10°, and 15°. We developed finite-element models for each acetabular position and performed a nonlinear contact analysis to calculate the joint contact pressure of the acetabular cartilage. The normal range of the maximum joint contact pressure was calculated to be < 4.1 MPa using a receiver operating characteristic curve. A paired t-test or Wilcoxon signed rank test with Bonferroni correction was used to compare joint contact pressures among acetabular positions. We evaluated the association of joint contact pressure with the patient-specific sagittal pelvic tilt and acetabular version and coverage using Pearson or Spearman correlation coefficients. An exploratory univariate logistic regression analysis was performed to identify which of the preoperative factors (CT measurement parameters and sagittal pelvic tilt) were associated with abnormal contact pressure after lateral rotation of the acetabulum. Variables with p values < 0.05 (anterior center-edge angle and sagittal pelvic tilt) were included in a multivariable model to identify the independent influence of each factor.

RESULTS

Lateral rotation of the acetabulum decreased the median maximum contact pressure compared with that before virtual PAO (3.7 MPa [range 2.2-6.7] versus 7.2 MPa [range 4.1-14 MPa], difference of medians 3.5 MPa; p < 0.001). The resulting maximum contact pressures were within the normal range (< 4.1 MPa) in 63% of the hips (24 of 38 hips). The maximum contact pressure after lateral acetabular rotation was negatively correlated with the standing pelvic tilt (anterior pelvic plane angle) (ρ = -0.52; p < 0.001) and anterior center-edge angle (ρ = -0.47; p = 0.003). After controlling for confounding variables such as the lateral center-edge angle and sagittal pelvic tilt, we found that a decreased preoperative anterior center-edge angle (per 1°; odds ratio 1.14 [95% CI 1.01-1.28]; p = 0.01) was independently associated with elevated contact pressure (≥ 4.1 MPa) after lateral rotation; a preoperative anterior center-edge angle < 32° in the standing pelvic position was associated with elevated contact pressure (sensitivity 57%, specificity 96%, area under the curve 0.77). Additional anterior rotation further decreased the joint contact pressure; the maximum contact pressures were within the normal range in 74% (28 of 38 hips), 76% (29 of 38 hips), and 84% (32 of 38 hips) of the hips when the acetabulum was rotated anteriorly by 5°, 10°, and 15°, respectively.

CONCLUSION

Via virtual PAO, normal joint contact pressure was achieved in 63% of patients by normalizing the lateral acetabular coverage. However, lateral acetabular rotation was insufficient to normalize the joint contact pressure in patients with more posteriorly tilted pelvises and anterior acetabular deficiency. In patients with a preoperative anterior center-edge angle < 32° in the standing pelvic position, additional anterior rotation is expected to be a useful guide to normalize the joint contact pressure.

CLINICAL RELEVANCE

This virtual PAO study suggests that biomechanics-based planning for PAO should incorporate not only the morphology of the hip but also the physiologic pelvic tilt in the weightbearing position in order to customize acetabular reorientation for each patient.

Ganz osteotomy for treatment of hip dysplasia through intra-pelvic approach. Early results

Ganz periacetabular osteotomy (PAO) is a technically demanding surgical procedure. It requires cutting around the acetabulum to mobilize it under fluoro- scopic control. The radiolucent table and good quality imaging are mandatory to perform this osteotomy in a safe way. Modification of Ganz osteotomy was developed a with minimal soft tissue exposure using intra-pelvic approach which allows direct visualization of the quadrilateral plate. The purpose of the present study was to review the early results in the initial group of patients who had this procedure. The Ganz PAO was performed on 8 cases painful dysplastic hips, using the intra-pelvic approach through the Pfannenstiel incision. All of the osteotomies were performed under fluoroscopic control and direct visualizing the osteotomy site from the same incision. The acetabular fragment was medialized and redirected anterolaterally then fixed with 3 screws. The pre-operative Harris hip score mean was 66.8 and improved to be 92.7 (p value <0.0005) and this was statistically significant. Radiologically the CEA improved in the pre-operative X-ray from mean of 13.12 degree to 28.37 degrees (p value <0.0005) and this was statistically significant. Painful dysplastic hips should be treated before function becomes seriously impaired. The Ganz osteotomy through an intra-pelvic approach, can be done with minimal exposure to radiation in a relatively short time.

Novel Utilization of Anterior Intrapelvic (Stoppa) Approach for Periacetabular Ganz Osteotomy: A Report of 2 Cases

CASE

The Ganz periacetabular osteotomy (PAO) is widely used to correct developmental hip dysplasia in the adolescent and young adult population. The aim of this case study was to examine the novel utility and safety of Stoppa approach for the Ganz PAO in a 15-year-old girl and 25-year-old man. The Stoppa approach is traditionally used for acetabular fractures, and its use for a Ganz PAO is relatively novel.

CONCLUSION

The Stoppa approach allows surgeons to successfully perform the Ganz PAO while simultaneously providing direct visualization for all osteotomies and vital structures.

Hip muscle and joint contact forces before, 6 and 12 months after minimally invasive periacetabular osteotomy

BACKGROUND

Previous studies on different periacetabular osteotomy approaches for correction of hip dysplasia disagree on the time course of normalisation of muscle function postoperatively, some stating that especially hip flexor function is not fully normalised after 12 months.

PURPOSE

The purpose of this study was to evaluate hip function during walking before, and 6 and 12 months after minimally invasive periacetabular osteotomy.

METHODS

Using conventional 3D inverse dynamics followed by static optimisation, we calculated hip net joint moment and angular impulse, as well as individual muscle forces and hip joint contact force, during walking for 32 patients with hip dysplasia and 32 matched controls.

RESULTS

None of the extensor and abductor measures were significantly different between controls and patients tested preoperatively, nor between any of the 3 time points patients were tested. For all of the flexor measures, patients' preoperative values were lower than controls', but had increased to values above the controls 6 months postoperatively.

CONCLUSION

Hip muscle function during walking seemed normalised after 6 months after minimally invasive periacetabular osteotomy, while joint contact force did not fully normalise until 12 months postoperatively, perhaps because the hip joint structures need a longer time to heal than the muscles and a potential pain alleviating strategy was still in effect.

TRIAL REGISTRY

Movement pattern in patients with hip dysplasia https://clinicaltrials.gov/ct2/show/NCT01344421, NCT01344421.

Isometric hip strength impairments in patients with hip dysplasia are improved but not normalized 1 year after periacetabular osteotomy: a cohort study of 82 patients

Background and purpose - In patients with hip dysplasia, knowledge of hip muscle strength after periacetabular osteotomy is lacking. We investigated isometric hip muscle strength in patients with hip dysplasia, before and 1 year after periacetabular osteotomy, and compared this with healthy volunteers. Furthermore, we investigated whether pre- to post-surgical changes in self-reported pain and sporting function were associated with changes in isometric hip muscle strength.Patients and methods - Isometric hip muscle strength was assessed twice in 82 patients (11 men) with a mean age of 30 (SD 9) years, before and 1 year after surgery, and once in 50 healthy volunteers. Isometric hip muscle strength was assessed with a hand-held dynamometer. Copenhagen Hip and Groin Outcome Score was used to measure self-reported outcome.Results - Despite 1-year improvements in isometric hip flexion (0.1 Nm/kg; 95% CI 0.06-0.2) and abduction (0.1 Nm/kg; CI 0.02-0.2), the patients' muscle strength was 13-34% lower than the strength of the healthy volunteers both pre- and post-surgery (p < 0.01). Moreover, changes in self-reported pain were associated with changes in hip flexion (13 points per Nm/kg; CI 1-26) and abduction (14 points per Nm/kg; CI 3-25), while changes in self-reported sporting function were associated with changes in hip extension (9 points per Nm/kg; CI 1-18).Interpretation - Isometric hip muscle strength is impaired in symptomatic dysplastic hips measured before periacetabular osteotomy. 1 year after surgery, isometric hip flexion and abduction strength had improved but muscle strength did not reach that of healthy volunteers.

Comparison of the modified Smith-Petersen (S-P) and ilioinguinal (I-I) approaches for periacetabular osteotomy in adult developmental dysplasia of the hip: a retrospective study

Background

Adult developmental dysplasia of the hip is an untreated congenital hip dysplasia that results in adult hip pain. One of the usual and effective methods for the treatment of this condition is periacetabular osteotomy. However, which approach is better between the modified S-P and the I-I approaches is still unclear and controversial.

Method and materials

We retrospectively assessed our experience with the modified S-P and the I-I approaches by inquiring and evaluating intraoperative blood loss, postoperative radiographic material, postoperative function of the hip, and related complications from July 2014 to January 2019.

Results

A total of 61 patients with adult developmental dysplasia of the hip were enrolled, and 33 patients were divided into a modified S-P group and 28 patients were divided into I-I group. The operation time and blood loss of group I-I were higher than that of group modified S-P. Other clinical and radiographic indexes showed no statistical significance between group the modified S-P and I-I groups.

Conclusion

There is no significant difference in the improvement of the function of the hip at the post-operation stage, but group I-I may require more operation time and blood loss at the intra-operation stage.

A New Rectus and Sartorius Sparing Approach for Periacetabular Osteotomy in Patients with Developmental Dysplasia of the Hip

Background: periacetabular osteotomy (PAO) is known as the gold standard surgical treatment in young adults with symptomatic hip dysplasia. With the aim of reducing soft tissue trauma, we developed a new rectus and sartorius sparing (RASS) approach. We hypothesized that this new PAO technique was equal regarding acetabular reorientation, complication rate, and short-term clinical outcome parameters, compared to our conventional, rectus sparing (RS) approach. Patients and Methods: we retrospectively assessed all PAO procedures performed by a single surgeon between 2016 and 2019 (n = 239 hips in 217 patients). The cases in which the new RASS technique were used (n = 48) were compared to the RS cases for acetabular orientation parameters, surgical time, perioperative reduction of hemoglobin level, and length of hospital stay (LOHS). Inclusion criteria were a lateral center-edge angle (LCEA) <25° and osteoarthritis Tönnis grade ≤1. Patients with acetabular retroversion or additional femoral osteotomy were excluded. Results: the mean patient age at the time of surgery was 29 years (14 to 50, SD ± 8.5). Females accounted for 79.5% in this series. The mean preoperative LCEA were 16° (7 to 24°, SD ± 4.4) and 15° (0 to 23°, SD ± 6) in the RASS and the RS group, respectively (p = 0.96). The mean preoperative acetabular index (AI) angles were 14° (2 to 25°, SD ± 4) and 14° (7 to 29°, SD ± 4.3), respectively (p = 0.67). The mean postoperative LCEA were significantly improved to 31° (25 to 37°, SD ± 3.5, p < 0.001) and 30.2° (20 to 38°, SD ± 4, p < 0.001), respectively. The mean postoperative AI angles improved to 2.8° (−3 to 13°, SD ± 3.3, p < 0.001) and 3° (−2 to 15°, SD ± 3.3, p < 0.001), respectively. There were no significant differences between the RASS and the RS group for surgical time, perioperative reduction in hemoglobin level, and LOHS. No blood transfusions were necessary perioperatively in either group. No major perioperative complication occurred in either group. We observed one surgical site infection (SSI) requiring superficial debridement in the RS group. Conclusion: the RASS approach for PAO showed to be a safe procedure with equivalent acetabular reorientation and equivalent clinical outcome parameters compared to the RS approach. Additionally, patients have fewer postoperative restrictions in mobilization with the RASS approach.

Transversus abdominis Plane Block for Improved Early Postoperative Pain Management after Periacetabular Osteotomy: A Randomized Clinical Trial

Background: Patients undergoing periacetabular osteotomy (PAO) may experience significant postoperative pain due to the extensive approach and multiple osteotomies. The aim of this study was to assess the efficacy of the transversus abdominis plane (TAP) block on reducing opioid consumption and improving clinical outcome in PAO patients. Patients and Methods: We conducted a two-group randomized-controlled trial in 42 consecutive patients undergoing a PAO for symptomatic developmental dysplasia of the hip (DDH). The study group received an ultrasound-guided TAP block with 20 mL of 0.75% ropivacaine prior to surgery. The control group did not receive a TAP block. All patients received a multimodal analgesia with nonsteroidal anti-inflammatory drugs (NSAID) (etoricoxib and metamizole) and an intravenous patient-controlled analgesia (PCA) with piritramide (1.5 mg bolus, 10 min lockout-time). The primary endpoint was opioid consumption within 48 h after surgery. Secondary endpoints were pain scores, assessment of postoperative nausea and vomiting (PONV), measurement of the quality of recovery using patient-reported outcome measure and length of hospital stay. Forty-one patients (n = 21 TAP block group, n = 20 control group) completed the study, per protocol. One patient was lost to follow-up. Thirty-three were women (88.5%) and eight men (19.5%). The mean age at the time of surgery was 28 years (18-43, SD ± 7.4). All TAP blocks were performed by an experienced senior anaesthesiologist and all operations were performed by a single, high volume surgeon. Results: The opioid consumption in the TAP block group was significantly lower compared to the control group at 6 (3 mg ± 2.8 vs. 10.8 mg ± 5.6, p < 0.0001), 24 (18.4 ± 16.2 vs. 30.8 ± 16.4, p = 0.01) and 48 h (29.1 mg ± 30.7 vs. 54.7 ± 29.6, p = 0.04) after surgery. Pain scores were significantly reduced in the TAP block group at 24 h after surgery. There were no other differences in secondary outcome parameters. No perioperative complication occurred in either group. Conclusion: Ultrasound-guided TAP block significantly reduces the perioperative opioid consumption in patients undergoing PAO.

Fast and automatic periacetabular osteotomy fragment pose estimation using intraoperatively implanted fiducials and single-view fluoroscopy

Accurate and consistent mental interpretation of fluoroscopy to determine the position and orientation of acetabular bone fragments in 3D space is difficult. We propose a computer assisted approach that uses a single fluoroscopic view and quickly reports the pose of an acetabular fragment without any user input or initialization. Intraoperatively, but prior to any osteotomies, two constellations of metallic ball-bearings (BBs) are injected into the wing of a patient's ilium and lateral superior pubic ramus. One constellation is located on the expected acetabular fragment, and the other is located on the remaining, larger, pelvis fragment. The 3D locations of each BB are reconstructed using three fluoroscopic views and 2D/3D registrations to a preoperative CT scan of the pelvis. The relative pose of the fragment is established by estimating the movement of the two BB constellations using a single fluoroscopic view taken after osteotomy and fragment relocation. BB detection and inter-view correspondences are automatically computed throughout the processing pipeline. The proposed method was evaluated on a multitude of fluoroscopic images collected from six cadaveric surgeries performed bilaterally on three specimens. Mean fragment rotation error was 2.4 ± 1.0 degrees, mean translation error was 2.1 ± 0.6 mm, and mean 3D lateral center edge angle error was 1.0 ± 0.5 degrees. The average runtime of the single-view pose estimation was 0.7 ± 0.2 s. The proposed method demonstrates accuracy similar to other state of the art systems which require optical tracking systems or multiple-view 2D/3D registrations with manual input. The errors reported on fragment poses and lateral center edge angles are within the margins required for accurate intraoperative evaluation of femoral head coverage.

Functional acetabular retroversion syndrome: description of a specific sub-type of FAI and results of treatment with minimally invasive PAO

INTRODUCTION

Acetabular retroversion syndrome is associated with pincer-type femoroacetabular impingement (FAI) and results, theoretically, from an externally rotated hemipelvis. The purpose of this study was to examine our surgical experience and the clinical results of functional acetabular retroversion syndrome treated with minimally-invasive periacetabular osteotomy (PAO).

METHODS

We performed a retrospective cohort study of prospectively collected data in consecutive patients who had an anteverting PAO from 01 November 2010 to 31 December 2015. All patients were followed up clinically and radiologically.Functional scores were ascertained using pre- and postoperative iHOT-12 and EQ-5D. The effect of hypermobility, smoking status and body mass index (BMI) on outcome measures was evaluated.

RESULTS

31 anteverting PAOs were performed on 27 consecutive patients. All patients were female. The mean age was 26.7 years (SD 6.7). The mean BMI was 25.8 kg/m² (SD 5.1). 5 patients were smokers (16.1%) and 11 exhibited signs of generalised joint laxity. 23 hips had undergone prior hip arthroscopy and 1 patient had previous open FAI surgery. The minimum clinical follow-up was 2 years (mean 3.4 years; range 2-7 years). A crossover sign was present in all cases. The mean iHOT-12 score improved from 19.5 to 51 at 6 months, 64.5 at 1 year and 48 at 2 years following surgery (p < 0.05) EQ-5D improved from 0.42 preoperatively to 0.76 at 6 months and 0.69 at 1 year following surgery (p < 0.05).

CONCLUSIONS

We have characterised functional acetabular retroversion syndrome (FARS) as a condition affecting young, active females which severe symptoms out of proportion to demonstrable radiographic pathology.

Surgical management of chronic pelvic instability following periacetabular osteotomy nonunion

INTRODUCTION

Periacetabular osteotomy (PAO) is an established treatment for symptomatic acetabular dysplasia in skeletally mature individuals without arthritis. Pelvic nonunion and associated stress fractures are under-reported. Nonunited stress fractures can cause continued buttock pain and pelvic instability. The aim of this study is to report on our experience managing patients with ongoing pain following nonunion of PAO.

PATIENTS AND METHODS

8 patients presented to a tertiary referral pelvic service with symptomatic PAO nonunion between 2015-2018. All patients underwent open reduction internal fixation of the superior pubic ramus nonunion, with ipsilateral iliac autograft, at an average of 48.1 (15-82) months following initial osteotomy. Demographic and perioperative data were recorded. Follow-up was on average to 9.9 months, once union was confirmed radiographically.

RESULTS

All patients were female and average age was 31.8 (18-41) years. In 7/8 (87.5%) patients a modified Stoppa approach was successfully utilised. 1 patient required an ilioinguinal approach due to the amount of rotational correction. All patients went on to union at the superior pubic ramus and reported improvement in mechanical symptoms. 5/8 (62.5%) patients were noted to develop union of the posterior column or inferior pubic ramus stress fracture indirectly. 2/8 (25%) patients developed progression of intra-articular pain, despite restoration of pelvic stability. 1 patient required intraoperative transfusion due to femoral vein injury. There were no other complications seen in this series.

CONCLUSIONS

To our knowledge, this is the largest case series of surgically managed PAO nonunion. Pelvic instability resulting from nonunion and stress fracture can be satisfactorily addressed by mobilising, grafting and plating the nonunion at the superior pubic ramus. The modified Stoppa approach is suitable in most cases, allowing excellent exposure whilst minimising the insult to soft tissues. The altered anatomy of the pelvis following PAO should be anticipated to reduce the risk to nearby neurovascular structures.

Is lateral acetabular rotation sufficient to correct anterolateral deficiency in periacetabular reorientation osteotomy? A CT-Based simulation study

BACKGROUND

Residual acetabular deficiency after periacetabular reorientation osteotomy can result in suboptimal outcome. The optimal algorithm of acetabular fragment correction to achieve normal anterolateral acetabular coverage is not well characterized. The aim of this study was to determine the prevalence of residual anterolateral deficiency after lateral acetabular rotation and to evaluate the ability of additional sagittal and axial rotation of the acetabulum to normalize the acetabular coverage in periacetabular osteotomy.

METHODS

We performed computed tomography-based simulated periacetabular osteotomy on 85 patients (85 hips) with hip dysplasia. The acetabular fragment was rotated laterally to achieve a lateral center-edge angle (CEA) of 30°. For hips with residual anterolateral deficiency, which were identified based on the reference interval of the anterior CEA, the acetabulum was further rotated in the sagittal or axial direction in 5-degree increments from 5° to 20°, and the ability of these two manoeuvres to restore a normal anterior CEA was assessed.

RESULTS

After lateral acetabular rotation, 16 hips (19%) had residual anterolateral deficiency, 67 hips (79%) had normal acetabular coverage, and 2 hips (2.4%) had acetabular overcoverage. A preoperative anterior CEA <37° predicted residual deficiency (sensitivity, 94%; specificity, 81%). Additional anterior sagittal rotation was more effective than posterior axial rotation in normalizing the anterior CEA, while minimizing the decrease in posterior CEA. The highest number of hips with normal anterior and posterior CEA was noted at 10° sagittal rotation (81%), which was followed by 15° sagittal rotation (63%).

CONCLUSIONS

Normal anterolateral coverage was achieved in 79% of patients after rotating the acetabulum laterally. However, lateral rotation of the acetabulum may be insufficient to correct the anterolateral deficiency in patients with an anterior CEA of <37°. In them, additional 10°-15° anterior sagittal rotation may be appropriate to achieve sufficient anterolateral coverage while retaining posterolateral coverage.

Extended Capture Range of Rigid 2D/3D Registration by Estimating Riemannian Pose Gradients

Traditional intensity-based 2D/3D registration requires near-perfect initialization in order for image similarity metrics to yield meaningful updates of X-ray pose and reduce the likelihood of getting trapped in a local minimum. The conventional approaches strongly depend on image appearance rather than content, and therefore, fail in revealing large pose offsets that substantially alter the appearance of the same structure. We complement traditional similarity metrics with a convolutional neural network-based (CNN-based) registration solution that captures large-range pose relations by extracting both local and contextual information, yielding meaningful X-ray pose updates without the need for accurate initialization. To register a 2D X-ray image and a 3D CT scan, our CNN accepts a target X-ray image and a digitally reconstructed radiograph at the current pose estimate as input and iteratively outputs pose updates in the direction of the pose gradient on the Riemannian Manifold. Our approach integrates seamlessly with conventional image-based registration frameworks, where long-range relations are captured primarily by our CNN-based method while short-range offsets are recovered accurately with an image similarity-based method. On both synthetic and real X-ray images of the human pelvis, we demonstrate that the proposed method can successfully recover large rotational and translational offsets, irrespective of initialization.

14-year hip survivorship after periacetabular osteotomy: a follow-up study on 1,385 hips

Background and purpose - Few studies have evaluated the long- and mid-term outcomes after minimally invasive periacetabular osteotomy (PAO). We investigated: (1) the long-term hip survival rate after PAO; (2) the risk of complications and additional surgery after PAO; and (3) the hip function at different follow-up points.Patients and methods - We reviewed 1,385 hips (1,126 patients) who underwent PAO between January 2004 and December 2017. Through inquiry to the Danish National Patient Registry we identified conversions to total hip arthroplasty (THA) and complications after PAO. We evaluated the Hip disability and Osteoarthritis Outcome Score (HOOS) obtained preoperatively, and at 6 months, 2-, 5-, and 10-years' follow-up.Results - 73 of the 1,385 hips were converted to THA. The overall Kaplan-Meier hip survival rate was 80% (95% CI 68-88) at 14 years with a mean follow-up of 5 years (0.03-14). 1.1% of the hips had a complication requiring surgical intervention. The most common additional surgery was removal of screws (13%) and 11% received a hip arthroscopy. At the 2-year follow-up, HOOS pain improved by a mean of 26 points (CI 24-28) and a HOOS pain score > 50 was observed in 86%.Interpretation - PAO preserved 4 of 5 hips at 14 years, with higher age leading to lower survivorship. The PAO technique was shown to be safe; 1.1% of patients had a complication that demanded surgical intervention. The majority of the patients with preserved hips have no or low pain. The operation is effective with a good clinical outcome.

Periacetabular osteotomy for hip dysplasia treatment through a mini-invasive technique. Our results at mid-term in 131 cases

BACKGROUND AND OBJECTIVE

Periacetabular osteotomy (PAO) is an accepted and worldwide technique recognized for residual dysplasia treatment and even in unstable hips with limited acetabular coverage. The aim of this study is to analyse the functional, radiological and complication results in patients treated with mini-invasive PAO.

MATERIAL AND METHODS

We performed a retrospective study in which we analysed 131 cases undergoing mini-invasive PAO at our centre. The degree of joint degeneration was evaluated with Tönnis scale, Wiberg angle, acetabular index (AI), anterior coverage angle (AC), joint space, complications and functional outcome with the Non-Arthritic Hip Score (NAHS) were analysed preoperatively and at the end of follow-up.

RESULTS

The average age was 32.3±9.5 (SD) years, 102 (77.9%) were female and 29 (22.1%) were male. 7.7±2.8 (SD) years follow up. The radiological parameters improved between the pre-surgical phase and the end of follow-up, Wiberg angle+18.5° (18.3° versus 36.8°, 95% CI 17.3 to 19.7), AC angle+13.5° (26.2° versus 39.7°, 95%CI 11.6 to 15.4) and the AI -11.1° (19.5° versus 8.4°; 95%CI -12.1 to -10,1). In addition, the functional results, with the NAHS scale, improved+31.3 points (60.7 pre-surgical versus 92 at the end of follow-up, 95% CI 28.7 to 33.8). The most common complication was transient lateral femoral cutaneous nerve hypoaesthesia in 10 cases (7%).

CONCLUSION

The mini-invasive PAO approach is a reproducible technique, it allows restoration of acetabular coverage and provides an improvement in functional scales as confirmed by our series.

Pose Estimation of Periacetabular Osteotomy Fragments With Intraoperative X-Ray Navigation

OBJECTIVE

State-of-the-art navigation systems for pelvic osteotomies use optical systems with external fiducials. In this paper, we propose the use of X-ray navigation for pose estimation of periacetabular fragments without fiducials.

METHODS

A two-dimensional/three-dimensional (2-D/3-D) registration pipeline was developed to recover fragment pose. This pipeline was tested through an extensive simulation study and six cadaveric surgeries. Using osteotomy boundaries in the fluoroscopic images, the preoperative plan was refined to more accurately match the intraoperative shape.

RESULTS

In simulation, average fragment pose errors were 1.3 ° /1.7 mm when the planned fragment matched the intraoperative fragment, 2.2 ° /2.1 mm when the plan was not updated to match the true shape, and 1.9 ° /2.0 mm when the fragment shape was intraoperatively estimated. In cadaver experiments, the average pose errors were 2.2  ° /2.2 mm, 3.8 ° /2.5 mm, and 3.5  ° /2.2 mm when registering with the actual fragment shape, a preoperative plan, and an intraoperatively refined plan, respectively. Average errors of the lateral center edge angle were less than 2 ° for all fragment shapes in simulation and cadaver experiments.

CONCLUSION

The proposed pipeline is capable of accurately reporting femoral head coverage within a range clinically identified for long-term joint survivability.

SIGNIFICANCE

Human interpretation of fragment pose is challenging and usually restricted to rotation about a single anatomical axis. The proposed pipeline provides an intraoperative estimate of rigid pose with respect to all anatomical axes, is compatible with minimally invasive incisions, and has no dependence on external fiducials.

Does pain and hip function improve 2 years after reverse periacetabular osteotomy? A follow-up study of 74 patients

Data on outcome in patients with acetabular retroversion (AR) treated with reverse periacetabular osteotomy (reverse PAO) are sparse. The aim of the study was to investigate changes in pain and hip function among patients with AR 2 years after reverse PAO and to examine whether changes in pain were associated with changes in hip function. In addition, to evaluate patient satisfaction and changes in quality of life (QoL). We present a prospective follow-up study with patient-reported outcome data from Aarhus University Hospital in Denmark. Pain at rest and during activity was measured with a Visual Analogue Scale (VAS), hip function with the Hip disability and Osteoarthritis Outcome Score (HOOS) and QoL with the Short-Form 36, pre-operatively and 2 years after reverse PAO in 74 patients. Changes were analysed using paired t-test and multiple linear regressions. Significant and clinically relevant mean improvements in pain and hip function were found. The numbers of responders achieving a minimal clinically important difference varied from 51 to 73%. Positive significant association between changes in pain and changes in hip function were found. Significant mean improvement in QoL was found. The study had a loss to follow-up of 23%. Two years after reverse PAO, patients diagnosed with AR showed significant and clinically relevant mean improvements in pain and hip function. Decreased pain was significantly associated with improved hip function. The majority of patients were satisfied with the result of surgery and QoL was similar to the Danish background population.

Efficacy of periacetabular osteotomy followed by progressive resistance training compared to progressive resistance training as non-surgical treatment in patients with hip dysplasia (PreserveHip) - a protocol for a randomised controlled trial

INTRODUCTION

Periacetabular osteotomy (PAO) is an established treatment for adolescent and adult patients with hip dysplasia. However, the efficacy of PAO has not been tested against another surgical intervention or conservative treatment in a randomised controlled trial before. We suggest that progressive resistance training (PRT) could be an alternative to PAO. The primary aim of this trial is therefore to examine the efficacy of PAO followed by 4 months of usual care followed by 8 months of PRT compared to 12 months of solely PRT in patients with hip dysplasia eligible for PAO in terms of patient-reported pain measured by The Copenhagen Hip and Groin Outcome Score (HAGOS).

METHODS AND ANALYSIS

This trial is a single-blinded multicentre randomised controlled clinical trial, where patients with hip dysplasia, who are eligible for PAO, will be randomised to either PAO followed by usual care and PRT or PRT only. Primary outcome is patient-reported pain, measured on the subscale pain on the HAGOS questionnaire 12 months after initiation of PAO or PRT. The key secondary outcomes are the other subscales of the HAGOS, adverse and serious adverse events, usage of painkillers (yes/no) and type of analgesics. Based on the sample size calculation, the trial needs to include 96 patients.

ETHICS AND DISSEMINATION

The trial is approved by the Central Denmark Region Committee on Biomedical Research Ethics (Journal No 1-10-72-234-18) and by the Danish Data Protection Agency (Journal No 1-16-02-120-19). The trial is also approved by The Regional Committee for Medical and Health Research Ethics, Region South-East Norway (Ref. 2018/1603). All results from this trial will be published in international peer-reviewed scientific journals regardless of whether the results are positive, negative or inconclusive.

TRIAL REGISTRATION NUMBER

NCT03941171.

High frequency of labral pathology in symptomatic borderline dysplasia: a prospective magnetic resonance arthrography study of 99 patients

Labral pathology is seen in both dysplastic and borderline dysplastic hips. Periacetabular osteotomy (PAO) is the treatment of choice for dysplasia. However, some authors have suggested that borderline dysplastic hips with concurrent labral pathology should be treated arthroscopically. The purpose of this study was to investigate the frequency of labral pathology between dysplastic and borderline dysplastic hips, whether centre-edge (CE) angle is associated with labral pathology, and finally if pain and labral pathology are associated. Ninety-nine symptomatic patients (104 hips) scheduled for PAO were examined. Five patients were excluded due to complaints from multiple joints and four failed to show at 2-year follow-up. Five patients did not fill out questionnaires preoperatively. Hips were characterized as dysplastic (CE angle <20°) and borderline dysplastic (CE angle 20° ≤ 25°). A magnetic resonance arthrography was performed, and labral pathology was classified according to the Czerny classification. Association with the CE angle, the acetabular index (AI) and preoperative WOMAC pain score was tested by multiple linear regression. There was no significant difference in frequency of labral pathology when comparing the two groups. Across the cohort, 86 of 99 patients had labral pathology. The CE angle was associated with increasing severity of labral pathology, whereas the AI angle and preoperative pain were not associated with labral pathology. Decreased lateral coverage adversely loads the labrum, predisposing it to tears. We advocate reorienting the biomechanical forces through PAO, not arthroscopic treatment. Level of pain was not associated with labral pathology, suggesting that labral pathology may not alone explain the dysplastic pain complex.

Isokinetic dynamometry and gait analysis reveal different hip joint status in patients with hip dysplasia

BACKGROUND:

Objective assessment of hip dysplasia patients' functional hip joint status routinely involves gait analysis or isokinetic dynamometry. However, these methods have shown equivocal results and have not been employed in the same groups of patients and controls.

PURPOSE:

To assess hip flexor and abductor moments by isokinetic dynamometry in the dysplasia patient and controls, for which we previously reported smaller flexor and slightly larger abductor moments during gait in patients compared to controls.

METHODS:

The study was designed as a prospective cohort study (Level of Evidence II) and conducted in a biomechanics laboratory at Aarhus University, Denmark, during 2011. Participants comprised 32 dysplasia patients and 32 age and gender matched controls. Outcome measures were static peak hip flexion moment at 15, 45 and 75° hip flexion; dynamic eccentric and concentric peak hip flexion moment at 60° and 120°/second; dynamic eccentric and concentric hip abductor moment at 30° and 60°/second.

RESULTS:

Hip dysplasia patients had smaller eccentric peak flexion moments and smaller eccentric and concentric peak abduction moments at all tested velocities.

CONCLUSION:

Although dysplasia patients have weaker hip flexion and abductor muscles than controls, their abductor muscles are sufficiently strong to ensure normal function during gait. Hence, gait analysis alone might not reveal the true, subnormal hip joint status in dysplasia patients. We suggest that comprehensive assessment of hip joint function in dysplasia patients should include more strenuous activities than gait, particularly in young(er) patients who are likely to prefer a more active lifestyle.

Patient-reported outcome and muscle-tendon pain after periacetabular osteotomy are related: 1-year follow-up in 82 patients with hip dysplasia

Background and purpose - Larger prospective studies investigating periacetabular osteotomy (PAO) with patient-reported outcome measures developed for young patients are lacking. We investigated changes in patient-reported outcome (PRO), changes in muscle-tendon pain, and any associations between them from before to 1 year after PAO. Patients and methods - Outcome after PAO was investigated in 82 patients. PRO was investigated with the Copenhagen Hip and Groin Outcome Score (HAGOS). Muscle-tendon pain in the hip and groin region was identified with standardized clinical tests, and any associations between them were analyzed with multivariable linear regressions. Results - HAGOS subscales improved statistically significantly from before to 1 year after PAO with effect sizes ranging from medium to very large (0.66-1.37). Muscle-tendon pain in the hip and groin region showed a large decrease in prevalence from 74% (95% CI 64-83) before PAO to 35% (95% CI 25-47) 1 year after PAO. Statistically significant associations were observed between changes in HAGOS and change in the sum of muscle-tendon pain, ranging from -4.7 (95% CI -8.4 to -1.0) to -8.2 (95% CI -13 to -3.3) HAGOS points per extra painful entity across all subscales from before to 1 year after PAO. Interpretation - Patients with hip dysplasia experience medium to very large improvements in PRO 1 year after PAO, associated with decreased muscle-tendon pain. The understanding of hip dysplasia as solely a joint disease should be reconsidered since muscle-tendon pain seems to play an important role in relation to the outcome after PAO.

Editorial Commentary: Hip Arthroscopy in Dysplastic Hip Population? A Must, a Maybe, or a No Go?

Treating symptomatic patients with dysplasia involves a controversy in therapy. The question is whether to obtain osseous correction with the help of pelvic reorientation osteotomy or to address intra-articular pathology with an arthroscopic approach. Neither isolated therapy nor the other method seems to be sufficient, but conducting both treatment options simultaneously has also not proved to be superior and carries the risk of additional complications. Different treatment options have been presented on this topic over the years and should be considered on a case-by-case basis. Pelvic reorientation osteotomy in patients with moderate to severe acetabular dysplasia remains uncontested, but it lacks the ability to obtain visualization of the central hip compartment. The isolated arthroscopic approach seems to be favorable for treatment of intra-articular pathologies in patients with mild to borderline dysplasia, whereas collateral arthroscopy in pelvic reorientation osteotomy may achieve better clinical outcomes in patients with more complex cases.

Does the physical activity profile change in patients with hip dysplasia from before to 1 year after periacetabular osteotomy?

Background and purpose - Knowledge of physical activity profiles among patients with hip dysplasia is lacking. We investigated whether patients with hip dysplasia change physical activity profile from before to 1 year after periacetabular osteotomy. Furthermore, we investigated associations between change in accelerometer-based physical activity and change in self-reported participation in preferred physical activities (PA). Patients and methods - Physical activity was objectively measured at very low to high intensity levels with accelerometer-based sensors. Subjectively, PA was recorded with Copenhagen Hip and Groin Outcome Score (HAGOS) in 77 patients. Associations between the 2 were analyzed with simple linear regression analyses. Results - Changes in accelerometer-based physical activity ranged from -2.2 to 4.0% points at all intensity levels from baseline to 1-year follow-up. These changes represent very small effect sizes (-0.16 to 0.14). In contrast, self-reported PA showed a statistically and clinically relevant increase of 22 (CI 14-29) HAGOS PA points 1 year post-surgery. Associations between change in accelerometer-based physical activity and change in self-reported PA were, however, not statistically significant and correspond to a percentage change in physical activity of only -0.87% to 0.65% for a change of 10 HAGOS PA points. Interpretation - Patients with hip dysplasia do not seem to change physical activity profile 1 year post-surgery if measured with objective accelerometer-based sensors. This is interesting as self-reported PA indicates that patients' ability to participate in physical activity increases, suggesting that this increased self-reported participatory capacity is not manifested as increased objectively measured physical activity.

Curved periacetabular osteotomy via a novel intermuscular approach between the sartorius and iliac muscles

INTRODUCTION

Herein, we describe and evaluate a curved periacetabular osteotomy (CPO) via an intermuscular approach (IM-CPO) between the sartorius and iliac muscles.

METHODS

Between January 2009 and January 2016, IM-CPO was performed in 17 joints (16 patients), and a traditional CPO was performed in 17 joints. The length of incision at wound closure, operative time, intraoperative blood loss, serum creatinine kinase (CK) level the day after surgery, correctional angle, walking ability assessed using the gait items of the Harris Hip Score (at 3 and 6 months after surgery), and perioperative complications were evaluated. Group differences were assessed using t-tests.

RESULTS

The IM-CPO and CPO groups did not differ in the mean operative time (130 minutes and 124 minutes, respectively), mean serum CK the day after surgery (349 IU/L and 425 IU/L, respectively), or mean correctional angle (24.9° and 24.6°, respectively). The mean incision length was significantly shorter in the IM-CPO group (8.3 cm) compared to that in the CPO group (9.5 cm). The mean walking ability was significantly higher in the IM-CPO group (24.2 points) compared to that in the CPO group (20.9 points) at 3 months after surgery, but not at 6 months after surgery (26.4 points and 24.9 points, respectively). No serious complications were observed in either group.

CONCLUSION

In addition to demonstrating a similarly satisfactory correctional angle, IM-CPO is anticipated to enable early weight-bearing and recovery of walking ability. Thus, IM-CPO is considered a superior surgical technique.

Biomechanical Guidance System for Periacetabular Osteotomy

This chapter presents a biomechanical guidance navigation system for performing periacetabular osteotomy (PAO) to treat developmental dysplasia of the hip. The main motivation of the biomechanical guidance system (BGS) is to plan and track the osteotomized fragment in real time during PAO while simplifying this challenging procedure. The BGS computes the three-dimensional position of the osteotomized fragment in terms of conventional anatomical angles and simulates biomechanical states of the joint. This chapter describes the BGS structure and its application using two different navigation approaches including optical tracking of the fragment and x-ray-based navigation. Both cadaver studies and preliminary clinical studies showed that the biomechanical planning is consistent with traditional PAO planning techniques and that the additional information provided by accurate 3D positioning of the fragment does not adversely impact the surgery.

Muscle-tendon-related abnormalities detected by ultrasonography are common in symptomatic hip dysplasia

INTRODUCTION

Hip dysplasia is characterized by reduced acetabular coverage of the femoral head leading to an increased mechanical load on the hip joint and the acting hip muscles. Potentially, the muscles and tendons functioning close to the hip joint may present with overuse-related ultrasonography findings. The primary aim was to report the prevalence of muscle-tendon-related abnormalities detected by ultrasonography in 100 patients with symptomatic hip dysplasia. The secondary aim was to investigate correlations between muscle-tendon-related abnormalities detected by ultrasonography and clinically identified pain related to muscles and tendons.

MATERIALS AND METHODS

One hundred patients (17 men) with a mean age of 29 ± 9 years were included. Muscle-tendon-related abnormalities were detected with a standardized ultrasound examination. Correlations between muscle-tendon-related abnormalities detected by ultrasonography and clinically identified pain related to muscles and tendons were tested with Spearman's rank correlation coefficient.

RESULTS

The most prevalent ultrasonography findings were identified in the iliopsoas tendon [50% (95% CI 40; 60)], the adductor longus tendon [31% (95% 22; 40)] and the gluteus medius/minimus tendons [27% (18; 36)]. Significant correlations between ultrasonography findings and pain related to muscles and tendons were only found for the iliopsoas tendon (ρ = 0.24 and p = 0.02) and the gluteus medius/minimus tendons (ρ = 0.35 and p < 0.001).

CONCLUSIONS

Muscle-tendon-related abnormalities detected by ultrasonography in the hip and groin region are common in patients with symptomatic hip dysplasia, and the ultrasonography findings of the iliopsoas and gluteus medius/minimus tendons are weakly to moderately correlated to pain related to muscles and tendons in these structures. Both the iliopsoas and the gluteus medius/minimus have a pronounced stabilizing role in the dysplastic hip joint, and the common muscle-tendon-related abnormalities in these patients may be caused by injuries related to excessive use or degenerative changes in the muscle-tendon tissue.

The interface between periacetabular osteotomy, hip arthroscopy and total hip arthroplasty in the young adult hip

Hip pain is highly prevalent in both the younger and the elderly population. In older patients, pain arising from osteoarthritis (OA) is most frequent, whereas in younger patients, non-degenerative diseases are more often the cause of pain. The pain may be caused by hip dysplasia and femoroacetabular impingement (FAI).Abnormal mechanics of the hip are hypothesized by some authors to cause up to 80% of OA in the hip. Therefore, correction of these abnormalities is of obvious importance when treating young patients with hip pain.Hip dysplasia can be diagnosed by measuring a CE angle < 25° on a plain standing radiograph of the pelvis.Dysplastic or retroverted acetabulum with significant symptoms should receive a periacetabular osteotomy (PAO).FAI with significant symptoms should be treated by adequate resection and, if necessary, labrum surgery.If risk factors for poor outcome of joint-preserving surgery are present (age > 45 to 50 years, presence of OA, joint space < 3 mm or reduced range of motion), the patient should be offered a total hip arthroplasty (THA) instead of PAO.THA can be performed following PAO with outcomes similar to a primary THA.Hip arthroscopy is indicated in FAI (cam and pincer) and/or for labral tears. Cite this article: EFORT Open Rev 2018;3:408-417. DOI: 10.1302/2058-5241.3.170042.

Reliability of computer-assisted periacetabular osteotomy using a minimally invasive approach

BACKGROUND

Periacetabular osteotomy (PAO) is the treatment of choice for younger patients with developmental hip dysplasia. The procedure aims to normalize the joint configuration, reduce the peak-pressure, and delay the development of osteoarthritis. The procedure is technically demanding and no previous study has validated the use of computer navigation with a minimally invasive transsartorial approach.

METHODS

Computer-assisted PAO was performed on ten patients. Patients underwent pre- and postoperative computed tomography (CT) scanning with a standardized protocol. Preoperative preparation consisted of outlining the lunate surface and segmenting the pelvis and femur from CT data. The Biomechanical Guidance System was used intra-operatively to automatically calculate diagnostic angles and peak-pressure measurements. Manual diagnostic angle measurements were performed based on pre- and postoperative CT. Differences in angle measurements were investigated with summary statistics, intraclass correlation coefficient, and Bland-Altman plots. The percentage postoperative change in peak-pressure was calculated.

RESULTS

Intra-operative reported angle measurements show a good agreement with manual angle measurements with intraclass correlation coefficient between 0.94 and 0.98. Computer navigation reported angle measurements were significantly higher for the posterior sector angle ([Formula: see text], [Formula: see text]) and the acetabular anteversion angle ([Formula: see text], [Formula: see text]). No significant difference was found for the center-edge ([Formula: see text]), acetabular index ([Formula: see text]), and anterior sector angle ([Formula: see text]). Peak-pressure after PAO decreased by a mean of 13% and was significantly different ([Formula: see text]).

CONCLUSIONS

We found that computer navigation can reliably be used with a minimally invasive transsartorial approach PAO. Angle measurements generally agree with manual measurements and peak-pressure was shown to decrease postoperatively. With further development, the system will become a valuable tool in the operating room for both experienced and less experienced surgeons performing PAO. Further studies with a larger cohort and follow-up will allow us to investigate the association with peak-pressure and postoperative outcome and pave the way to clinical introduction.

Aspirin provides adequate VTE prophylaxis for patients undergoing hip preservation surgery, including periacetabular osteotomy

There are no clear guidelines regarding optimal venous thromboembolism (VTE) prophylaxis for patients undergoing hip preservation surgery (HPS), in particular pelvic osteotomy, which is considered to be a major orthopaedic procedure. The aim of this study was to determine the efficacy of aspirin for VTE prophylaxis in a large cohort of patients undergoing femoroacetabular osteoplasty (FAO) and periacetabular osteotomy (PAO). This was a retrospective study of prospectively collected data on patients undergoing HPS. A total of 603 patients (643 cases) underwent FAO and 80 patients (87 cases) underwent PAO between 2003 and 2016. The mean age of patients was 34.3 years (range 14.3–68.1 years). The type of VTE prophylaxis administered changed over time with earlier patients receiving warfarin (44 cases), followed by aspirin at 325 mg twice daily (448 cases), and most recently aspirin 81 mg twice daily (238 cases). The complications of symptomatic pulmonary embolism (PE), deep venous thrombosis (DVT) and major bleeding events within 90 days of surgery were documented. There were zero patients that developed major bleeding events or required evacuation of a hematoma. One patient who underwent FAO and received aspirin 325 mg, developed post-operative symptomatic DVT. One patient who underwent PAO and received aspirin 325 mg developed DVT and PE. This study demonstrates that the incidence of VTE following joint preservation procedure is acceptably low. Administration of aspirin to patients undergoing FAO or PAO appears to be adequate in reducing the risk of VTE. Only two patients in this cohort developed VTE following HPS.

Minimally invasive (MIS) Tönnis osteotomy- A technical annotation and review of short term results

Aims

We detail a modified single incision approach to perform the Tonnis triple pelvic osteotomy by a minimally invasive approach.

Patients and Methods

12 children underwent minimally invasive Tonnis Osteotomy. There were five boys and seven girls in this study group. Average age was 11 years (9-15 years) at the time of surgery. Mean follow-up was 20.5 months (13-39 months).

Results

The average preoperative Antero-Posterior (AP) Centre Edge (CE) angle was -8.8° (-38.6°-18°), the average post-operative AP CE angle was 29.7° (25.1°-43.7°). The average preoperative lateral CE angle was -4.7° (-16°-0°), the average postoperative Lateral CE angle was 28.5° (21.3°-37.4°). The Sharp's angle before and after surgery were 55.7° (51.3°-66°) and 32.4° (16.1°-40.1°) respectively. The mean Tönnis angle before and after the osteotomy were 28.86° (19.7°-43.4°) and 6.3° (0.5°-9.4°) respectively. There was one major complication with sciatic nerve palsy which is in the recovery phase on followup and six minor complications including two cases of transient lateral femoral cutaneous nerve injury, two cases of ischial non-union, over granulation of the wound in one case, and metalwork irritation in one case.

Conclusion

We have described a minimally invasive Tonnis osteotomy as a viable option based on our results. This technique is recommended for those who are conversant with the traditional pelvicosteotomies.

Periacetabular osteotomy for developmental hip dysplasia with labral tears: is arthrotomy or arthroscopy required?

Patients with developmental dysplasia of the hip (DDH) who undergo periacetabular osteotomy (PAO) often have labral tears. The objective of this retrospective study was to compare PAO alone with PAO combined with arthrotomy or arthroscopy in DDH patients who had a full-thickness labral tear on magnetic resonance imaging. In total, 47 hips in the PAO group (PAO) were compared with 60 hips in the PAO with concomitant arthrotomy or arthroscopy (PAO-A) with respect to Hip Disability and Osteoarthritis Outcome Score (HOOS), modified Harris Hip Score (mHHS), Visual Analog Scale (VAS), clinical and radiographic outcomes at a median of 29 months. Reoperation rate and complications were compared between two groups of treatment. The PAO group was younger than the PAO-A group (25.2 ± 9.7 versus 31.3 ± 8.3). The PAO group was more likely to have worse dysplasia: lateral center edge angle (7.6°±9.63° versus 10.8°±6.85°) and anterior center edge angle (4°±12.92° versus 10.8°±9.92°). The PAO group had a higher preoperative mHHS (65.2 ± 15.3 versus 57.8 ± 14.8) and HOOS (66.3 ± 17.5 versus 55.8 ± 20.1). There were no significant differences in final functional outcome scores across treatment groups: mHHS (PAO; 86.8 ± 12.4 versus PAO-A, 83.3 ± 17.2), HOOS (86.5 ± 13.3 versus 82.5 ± 16.8) and VAS (2.5 ± 2.8 versus 2.5 ± 3.1). There was no difference in reoperation rate between two groups (6.4% versus 11.6%, P = 0.51). The overall complication rate was lower in the PAO group (26% versus 68%), but major complications were comparable. On the basis of our data, we were not able to conclusively demonstrate a clear benefit for the routine treatment of all labral tears; however, arthrotomy or arthroscopy may play a role in some conditions.

Muscle-tendon-related pain in 100 patients with hip dysplasia: prevalence and associations with self-reported hip disability and muscle strength

The primary aim was to identify muscle-tendon-related pain in 100 patients with hip dysplasia. The secondary aim was to test whether muscle-tendon-related pain is associated with self-reported hip disability and muscle strength in patient with hip dysplasia. One hundred patients (17 men) with a mean age of 29 years (SD 9) were included. Clinical entity approach was carried out to identify muscle-tendon-related pain. Associations between muscle-tendon-related pain and self-reported hip disability and muscle strength were tested with multiple regression analysis, including adjustments for age and gender. Self-reported hip disability was recorded with the Copenhagen Hip and Groin Outcome Score (HAGOS), and muscle strength was assessed with a handheld dynamometer. Iliopsoas- and abductor-related pain were most prevalent with prevalences of 56% (CI 46; 66) and 42% (CI 32; 52), respectively. Adductor-, hamstrings- and rectus abdominis-related pain were less common. There was a significant inverse linear association between muscle-tendon-related pain and self-reported hip disability ranging from −3.35 to − 7.51 HAGOS points in the adjusted analysis (P < 0.05). Besides the association between muscle-tendon-related pain and hip extension a significant inverse linear association between muscle-tendon-related pain and muscle strength was found ranging from −0.11 to − 0.12 Nm/kg in the adjusted analysis (P < 0.05). Muscle-tendon-related pain exists in about half of patients with hip dysplasia with a high prevalence of muscle-tendon-related pain in the iliopsoas and the hip abductors and affects patients' self-reported hip disability and muscle strength negatively.

Functional results in periacetabular osteotomy: is it possible to obtain a normal gait after the surgery?

INTRODUCTION

Gait analysis is one of the poorly understood dimensions of the functional results obtained after periacetabular osteotomy (PAO) due to dysplasia of the hip.

MATERIALS AND METHODS

Spatiotemporal parameters as well as coronal and sagittal plane kinematics and moments were compared among three demographically similar groups of subjects: (i) 23 patients with excellent results according to the Harris Hip Score (HHS) (mean 6.6 years of follow-up); (ii) 12 patients with good and fair results according to the HHS (mean 9.3 years of follow-up); and (iii) 35 asymptomatic controls.

RESULTS

50% of the analysed sagittal plane kinematic parameters were significantly better (p<0.05) in the control group not only for the hip joint but also for the ipsilateral knee and ipsilateral ankle. A vast majority of the other evaluated gait parameters resulted similar among the groups (p>0.05).

CONCLUSIONS

In our experience, most of the gait parameters after PAO are close to those observed in control subjects; however, the obtained pattern cannot be classified as a completely normal gait. The excellence in terms of functional results seems not to be determined by the achievement of this theoretical goal.