Minimally invasive periacetabular osteotomy using a modified Smith-Petersen approach: technique and early outcomes

Comparison of Two Surgical Approaches for Periacetabular Osteotomy: A Retrospective Study of Patients with Developmental Dysplasia of the Hip

OBJECTIVE

Given the intricate challenges and potential complications associated with periacetabular osteotomy (PAO) for developmental dysplasia of the hip (DDH). Our study aimed to compare the clinical and imaging benefits and drawbacks of two surgical approaches, the modified Stoppa combined iliac spine approach and the modified Smith-Peterson approach, for treating PAO and to provide guidance for selecting clinical approaches.

METHODS

A retrospective analysis of 56 patients with 62 DDHs was conducted from June 2018 to January 2022. The experimental group underwent surgery via the modified Stoppa combined iliac spine approach, while the control group underwent surgery via the modified Smith-Peterson approach for periacetabular osteotomy and internal fixation. Basic statistical parameters, including age, sex, BMI, and preoperative imaging data, were analyzed. Differences in surgical time, intraoperative blood loss, and postoperative imaging data were compared, as were differences in preoperative and postoperative imaging data between the two groups.

RESULTS

There were 28 hips in the experimental group and 34 in the control group. Moreover, there was no significant difference in the basic parameters between the experimental and control groups. Before and after the operation, for the LCE angle, ACE angle, and Tonnis angle, there was no significant difference in acetabular coverage (p > 0.05). However, there were significant differences between the two groups in terms of the above four indicators before and after the operation (p < 0.05). After the operation, the experimental group exhibited significant increases in both lateral and anterior acetabular coverage of the femoral head. However, the experimental group had longer operation times and greater bleeding volumes than did the control group. Despite this, the experimental group demonstrated significant advantages in protecting the lateral femoral cutaneous nerve compared to the control group.

CONCLUSION

The modified Stoppa combined iliac spine approach can be considered a practical approach for PAO and is more suitable for patients with DDH who plan to be treated by one operation than the classic modified Smith-Peterson approach for PAO.

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.

Making the cut: a technical note and literature review of Bernese periacetabular osteotomy techniques with special attention to ischial osteotomy initiation and completion with an inside to anterior curved osteotomy

Periacetabular osteotomy includes a fluoroscopy-guided ischial cut without direct visualization. Previously described techniques include a mediolateral ischial cortex cut, which is associated with the risk of injuring nearby nerves. Another drawback of that technique is the difficulty connecting an ischial cortex cut with a retroacetabular cut due to orthogonal nature of the osteotomy. In general, an additional cut from medial to lateral is required. The present study aimed to describe a technique that eliminates those problems due to use of only a central cut of the ischium and the curved nature of the osteotomy.

Pain, function and quality of life are impaired in adults undergoing periacetabular osteotomy (PAO) for hip dysplasia: a systematic review and meta-analysis

BACKGROUND

Hip dysplasia is a common condition in active adults with hip pain that can lead to joint degeneration. Periacetabular osteotomy (PAO) is a common surgical treatment for hip dysplasia. The effect of this surgery on pain, function and quality of life (QOL) has not been systematically analysed.

PURPOSE

In adults with hip dysplasia: (1) evaluate differences in pain, function and QOL in those undergoing PAO and healthy controls; (2) evaluate pre- to post-PAO changes in pain, function and QOL; (3) evaluate differences in pain, function and QOL in those with mild versus severe dysplasia, undergoing PAO; and (4) evaluate differences in pain, function and QOL in those having primary PAO versus those with previous hip arthroscopy.

METHODS

A comprehensive, reproducible search strategy was performed on 5 different databases. We included studies that assessed pain, function and QOL in adults undergoing PAO for hip dysplasia, using hip-specific patient reported outcomes measures.

RESULTS

From 5017 titles and abstracts screened, 62 studies were included. Meta-analysis showed PAO patients had worse outcomes pre- and post-PAO compared to healthy participants. Specifically, pain (standardised mean difference [SMD] 95% confidence interval [CI]): -4.05; -4.78 to -3.32), function (-2.81; -3.89 to -1.74), and QOL (-4.10; -4.43 to -3.77) were significantly poorer preoperatively.Meta-analysis found patients experienced improvements following PAO. Pain improved from pre-surgery to 1-year (standardised paired difference [SPD] 1.35; 95% CI, 1.02-1.67) and 2 years postoperatively (1.35; 1.16-1.54). For function, the activities of daily living scores at 1 year (1.22; 1.09-1.35) and 2 years (1.06; 0.9-1.22) and QOL at 1 year (1.36; 1.22-1.5) and 2 years (1.3; 1.1-1.5) all improved. No difference was found between patients undergoing PAO with mild versus severe dysplasia.

CONCLUSIONS

Before undergoing PAO surgery, adults with hip dysplasia have worse levels of pain, function and QOL compared to healthy participants. These levels improve following PAO, but do not reach the same level as their healthy participants.

REGISTRATION

PROSPERO (CRD42020144748).

Prevention of motor ascending branch of the rectus femoris injuries in Bernese periacetabular osteotomy: a cadaveric study

The Bernese periacetabular osteotomy (PAO) is a surgical procedure used to treat hip dysplasia in young adults, but it carries the risk of neurological complications, including injury to the motor ascending branch of the rectus femoris (MABRF). This study aimed to describe anatomical considerations to prevent MABRF injuries during PAO. A cadaveric study was conducted on seven specimens. The original and modified PAO approaches were used, with and without disinsertion of the rectus femoris muscle origin. The femoral nerve was dissected in all specimens from the endopelvic position to the MABRF origin (T-point). The average distance from the anterosuperior iliac spine to the T-point was 10.2 ± 0.4 cm. To protect the MABRF, a safety zone was identified for the osteotome placement during the ischial cut. The osteotome was slid over the joint capsule, deflecting the iliocapsularis muscle medially and distally. This manoeuvre shields the MABRF with the iliocapsularis muscle, reducing the risk of neurological injury. Both the original and modified PAO approaches were considered safe techniques with low risk to the rectus femoris innervation. These findings offer valuable insights for surgeons performing PAO, emphasizing the significance of understanding anatomical relationships and implementing protective measures to enhance patient outcomes and minimize complications. In conclusion, implementing these anatomical considerations can help prevent MABRF injuries during PAO, contributing to safer and more successful surgical interventions for hip dysplasia in young adults.

Acetabular Sector Angles in Asymptomatic and Dysplastic Hips: Defining Dysplasia and Thresholds to Guide Management

BACKGROUND

Radiographic evaluation plays an important role in detecting and grading hip dysplasia. Acetabular sector angles (ASAs) measure the degree of femoral head coverage provided by the acetabulum on computed tomographic (CT) scans. In this study, we aimed to determine ASA values at different axial levels in a control cohort with asymptomatic, high-functioning hips without underlying hip pathology and a study group with symptomatic, dysplastic hips that underwent periacetabular osteotomy (PAO), thereby defining the ASA thresholds for hip dysplasia.

METHODS

This was a cross-sectional study evaluating a control group of 51 patients (102 hips) and a study group of 66 patients (72 hips). The control group was high-functioning and asymptomatic, with an Oxford Hip Score of >43, did not have osteoarthritis (Tönnis grade ≤1), underwent a pelvic CT scan, had a mean age (and standard deviation) of 52.1 ± 5.5 years, and was 52.9% female. The study group had symptomatic hip dysplasia treated with PAO, had a mean age of 29.5 ± 7.3 years, and 83.3% was female. Anterior ASA (AASA) and posterior ASA (PASA) were measured at 3 axial CT levels to determine equatorial, intermediate, and proximal ASA. The thresholds for dysplasia were determined using receiver operating characteristic (ROC) curve analysis, including the area under the curve (AUC).

RESULTS

Patients with dysplasia had significantly smaller ASAs compared with the control group; the differences were most pronounced for proximal AASAs and proximal and intermediate PASAs. The control group had a mean proximal PASA of 162° ± 17°, yielding a threshold for dysplasia of 137° (AUC, 0.908). The mean intermediate PASA for the control group was 117° ± 11°, yielding a threshold of 107° (AUC, 0.904). The threshold for anterior dysplasia was 133° for proximal AASA (AUC, 0.859) and 57° for equatorial AASA (AUC, 0.868). The threshold for posterior dysplasia was 102° for intermediate PASA (AUC, 0.933).

CONCLUSIONS

Measurement of ASA is a reliable tool to identify focal acetabular deficiency with high accuracy, aiding diagnosis and management. A proximal PASA of <137° or an intermediate PASA of <107° should alert clinicians to the presence of dysplasia.

LEVEL OF EVIDENCE

Diagnostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Research on anterior minimally invasive approach in the treatment of children with developmental dysplasia of the hip

OBJECTIVES

To investigate the clinical efficacy and safety of open reduction through anterior minimally invasive approach in the treatment of children with developmental dysplasia of the hip.

METHOD

A total of 23 patients (25 hips) less than 2 years with developmental dysplasia of the hip treated by open reduction through anterior minimally invasive approach were treated in our hospital from August 2016 to March 2019. Through the anterior minimally invasive approach, we enter from the gap between sartorius muscle and tensor fasciae lata without cutting off rectus femoris muscle, which can effectively expose the joint capsule and reduce the damage to medial blood vessels and nerves. The operation time, incision length, intraoperative bleeding, hospital stay and surgical complications were observed. The progression of developmental dysplasia of the hip and avascular necrosis of the femoral head were evaluated by imaging examination.

RESULT

All patients were performed with follow-up visit for an average of 22 months. The average incision length was 2.5 cm, the average operation time was 26 min, the average intraoperative bleeding was 12ml, and the average hospital stay was 4.9 days. All patients received concentric reduction immediately after operation, and no re-dislocation occurred. At the last follow-up visit, the acetabular index was (25.8 ± 6.4°). During the follow-up visit, X-ray showed avascular necrosis of the femoral head in 4 hips (16%).

CONCLUSION

open reduction through anterior minimally invasive approach can achieve good clinical effect in the treatment of infantile developmental dysplasia of the hip.

Current Surgical Techniques in the Treatment of Adult Developmental Dysplasia of the Hip

The surgical protocols currently used for the treatment of developmental dysplasia of the hip (DDH) are varied, with sufficient differences in clinical outcomes that warrant a review of the role of practicing orthopedic surgeons. This paper aims to summarize the current novel techniques within the realm of surgical treatment for adult DDH, thus serving as a guide to surgeons looking to quickly familiarize themselves with available techniques. We performed computer systematic literature searches of the Embase and PubMed databases from 2010 to 2 April 2022. Study parameters as well as their respective patient reported outcomes (PROMs) were described in detail and compiled into diagrams. Two novel techniques were identified for the treatment of borderline or low-grade DDH. Six techniques which included modifications to the Bernese periacetabular osteotomy (PAO) were identified for the treatment of symptomatic DDH. Three techniques which include combinations of arthroscopy and osteotomy were identified for the treatment of DDH with concomitant hip pathologies such as cam deformities. Finally, six techniques, all of which are modifications to total hip arthroplasty (THA), were identified for the treatment of high-grade DDH. The techniques detailed in this review therefore equip surgeons with the necessary knowledge to improve outcomes in patients with varying degrees of DDH.

[Hip dysplasia: What influence do age, arthrosis and concomitant diseases have on the treatment result?]

Pelvic osteotomies are an established treatment for symptomatic adult hip dysplasia with a promising long-term outcome. Results depend not only on the achieved acetabular reorientation but also on patient-factors like preoperative joint condition (degree of osteoarthritis and joint congruency) and age. Additionally, the diagnosis and appropriate therapy of impingement-associated hip deformities is essential in order to achieve good mid- and long-term outcomes. The influence of chondrolabral pathology on the outcome of pelvic osteotomies is not yet defined. Symptomatic patients with residual dysplasia after previous pelvic or acetabular osteotomies can benefit from an additional osteotomy, although results can be worse in comparison to prior unoperated joints. Obesity can make surgery more demanding and increases the complication profile of PAO, although it has no influence on the postoperative outcome. Regarding the overall prognosis after an osteotomy, the consideration of combined risk factors is superior to the concentration on individual factors alone.

A minimally invasive periacetabular osteotomy improves the radiographic parameters and functional outcomes in the treatment of developmental dysplasia of the hip in adolescents and adults: surgical technique and early results

PURPOSE

To introduce West China Hospital periacetabular osteotomy (WCH PAO) for acetabular dysplasia in adolescent and young adult patients and evaluate the early clinical results of WCH PAO.

METHODS

A retrospective analysis of 34 patients with developmental dysplasia of the hip was performed from October 2019 to April 2021. Baseline data with surgical time and perioperative blood-loss volume were retrieved from medical record systems. The lateral center-to-edge angle (LCEA), acetabular inclination (AI), hip disability and osteoarthritis outcome score (HOOS), University of California Los Angeles (UCLA), and modified Harris hip score (mHHS) were compared preoperatively and postoperatively.

RESULTS

All patients had significant postoperative radiology improvements, including LCEA and AI. The LCEA was improved from 12.9 to 33.2°, and the AI was decreased from 27.2 to 8.5°. In addition, hip functional outcomes, including HOOS, UCLA and mHHS, were improved. The UCLA was improved from 3.9 to 6.3, and the HOOS was decreased from 71.0 to 10.5. The Harris hip score improved from 50.8 before surgery to 87.4 after surgery. The mean operative time was 155 min (range 120 to 190 min), and the mean intra-operative blood loss was 580.2 ± 285.5 ml. Furthermore, no major complications, including nerve injury or bone nonunion, occurred in the cohort study.

CONCLUSION

WCH PAO is a minimally invasive surgical method for acetabular dysplasia in adolescent and young adult patients who that simplifies the surgical procedure and decreases the incidence of complications related to osteotomy.

Intraoperative Fluoroscopy Allows the Reliable Assessment of Deformity Correction during Periacetabular Osteotomy

We aimed to determine the accuracy and reliability of measures characterizing anterior, lateral, and posterior acetabular coverage on intraoperative fluoroscopic images compared to postoperative radiographs when performing periacetabular osteotomies (PAOs). A study involving 100 PAOs was initiated applying a standardized intraoperative imaging protocol. Coverage was determined by the lateral center edge angle (LCEA), the Tönnis angle (TA), and the anterior and posterior wall index (AWI, PWI). An intraclass correlation coefficient (ICC) model was used to assess interrater (ICC (3,2)) and intrarater (ICC (2,1)) reliability. The ICC (2,2) between analyses obtained from intraoperative fluoroscopy and postoperative radiographs and the corresponding 95% confidence interval (CI) were determined and complemented by Bland–Altman analysis, the mean difference, and 95% limits of agreement (LOA). The ICCs were 0.849 for the LCEA (95% CI 0.783–0.896), 0.897 for the TA (95% CI 0.851–0.930), 0.864 for the AWI (95% CI 0.804–0.907), and 0.804 for the PWI (0.722–0.864). The assessed interrater reliability was excellent except for the AWI, which was graded good (ICC = 0.857, 95% CI 0.794–0.902). Interrater agreement was generally good and fair for the AWI (ICC = 0.715, 95% CI 0.603–0.780). For each postoperative radiograph, interrater reliability was good with ICCs ranging from 0.813 (TA) to 0.881 (PWI). Intrarater reliability was good for all measurements and excellent for the preoperative TA (ICC = 0.993, 95% CI 0.984–0.997) and PWI (ICC = 0.954, 95% CI 0.919–0.97). In summary, we confirm the validity and reliability of intraoperative fluoroscopy as an alternative imaging modality to radiography to evaluate acetabular fragment orientation during PAO. We affirm the LCEA and TA as precise measures for lateral head coverage, and show the suitability of the AWI and PWI to steadily assess acetabular version.

Comparison of Acetabular Measurements Between 2 Validated Software Programs Used in Hip Preservation Surgery

BACKGROUND

Validated software tools (Clinical Graphics [CG] and Hip²Norm) permit measurement of the percentage of femoral head coverage (%FHC), which aids in morphological classification and prediction of outcome after hip preservation surgery.

PURPOSE

(1) To assess whether acetabular parameter measurements determined from 2 commonly used software systems are comparable. (2) To determine which parameters influence the correlation or differences between software outputs and measurements.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

The study included 69 patients (90 hips) who underwent periacetabular osteotomy and had comprehensive preoperative imaging available. Lateral center-edge angle (LCEA), acetabular index (AI), and %FHC were determined using 3-dimensional computed tomography (CT) measurements by CG and Hip²Norm software. Images of 18 pelvises were segmented to determine spinopelvic parameters and subtended acetabular angles. Between-group measurements were compared using correlation coefficients and Bland-Altman analyses. The difference in the outputs of the 2 programs was defined as delta (Δ). Radiographic parameters were tested to assess whether they were responsible for differences in %FHC between software programs.

RESULTS

Strong correlations between LCEA (ρ = 0.862) and AI (ρ = 0.825) measurements were seen between the Hip²Norm and CG programs. However, weak correlation was seen in the estimate of %FHC (ρ = 0.358), with the presence of a systematic error. Hip²Norm consistently produced lower anterior, posterior, and total %FHC values than CG. The %FHC determined by CG, but not Hip²Norm, correlated with acetabular subtended angles (P < .05). Pelvic tilt measured on CT did not correlate with pelvic tilt estimated by Hip²Norm (P = .56), and ΔPelvicTilt strongly correlated with the difference in %FHC by the 2 software programs (ρ = 0.63; P = .005), pelvic incidence (ρ = 0.73; P < .001), and pelvic tilt (ρ = -0.91; P < .001) as per CT.

CONCLUSION

The correlation of %FHC between Hip²Norm and CG was weak (ρ = 0.358). The difference in measurements of %FHC correlated with ΔPelvicTilt. The %FHC determined by CG strongly correlated with the segmented acetabular subtended angles and thus more likely reflected true values. Hip preservation surgeons should be aware of these measurement differences because %FHC is important in the diagnosis and prognosis of acetabular dysplasia.

Pelvic tilt from supine to standing in patients with symptomatic acetabular retroversion of the hip

AIMS

Acetabular retroversion is a recognized cause of hip impingement and can be influenced by pelvic tilt (PT), which changes in different functional positions. Positional changes in PT have not previously been studied in patients with acetabular retroversion.

METHODS

Supine and standing anteroposterior (AP) pelvic radiographs were retrospectively analyzed in 69 patients treated for symptomatic acetabular retroversion. Measurements were made for acetabular index (AI), lateral centre-edge angle (LCEA), crossover index, ischial spine sign, and posterior wall sign. The change in the angle of PT was measured both by the sacro-femoral-pubic (SFP) angle and the pubic symphysis to sacroiliac (PS-SI) index.

RESULTS

In the supine position, the mean PT (by SFP) was 1.05° (SD 3.77°), which changed on standing to a PT of 8.64° (SD 5.34°). A significant increase in posterior PT from supine to standing of 7.59° (SD 4.5°; SFP angle) and 5.89° (SD 3.33°; PS-SI index) was calculated (p < 0.001). There was a good correlation in PT change between measurements using SFP angle and PS-SI index (0.901 in the preoperative group and 0.815 in the postoperative group). Signs of retroversion were significantly reduced in standing radiographs compared to supine: crossover index (0.16 (SD 0.16) vs 0.38 (SD 0.15); p < 0.001), crossover sign (19/28 hips vs 28/28 hips; p < 0.001), ischial spine sign (10/28 hips vs 26/28 hips; p < 0.001), and posterior wall sign (12/28 hips vs 24/28 hips; p < 0.001).

CONCLUSION

Posterior PT increased from supine to standing in patients with symptomatic acetabular retroversion. The features of acetabular retroversion were less evident on standing radiographs. The low PT angle in the supine position is a factor in the increased appearance of acetabular retroversion. Patients presenting with symptoms of hip impingement should be assessed by supine and standing pelvic radiographs to highlight signs of acetabular retroversion, and to assist with optimizing acetabular correction at the time of surgery. Cite this article: Bone Joint J 2022;104-B(7):786-791.

Treatment of symptomatic hip dysplasia by posterolateral small incision assisted Bernese periacetabular osteotomy

Background

For periacetabular osteotomy, traditional approaches usually have a long learning curve. We aimed to evaluate the postoperative results and complications of periacetabular osteotomy under a new double-incision approach.

Methods

The records of 58 consecutive patients (65 hips) who underwent periacetabular osteotomy using the new approach were retrospectively reviewed and evaluated. There were 52 women and 6 men with a mean age of 28.1 years at the time of surgery.

Results

The average follow-up period was 35.2 months, during which no patients were converted to total hip arthroplasty. Complications included 6 hips (9.2%) with nerve dysesthesias and 1 hip (1.5%) with delayed wound healing. The mean operative time and intraoperative blood loss were 88.6 min and 402.8 ml, respectively. The mean modified Harris hip score had improved from 72.2 points preoperatively to 91.3 points at the last follow-up. Fifty-five patients (62 hips, 95.4%) were satisfied to their outcomes, and good preoperative functional score was associated with a satisfactory outcome. Furthermore, the average lateral center–edge angle, anterior center–edge angle and acetabular index angle were corrected well after surgery.

Conclusion

Periacetabular osteotomy using modified Smith-Petersen or Bikini approach with posterolateral assisted small incision can be performed safely and with satisfactory results. In addition, this technique shortens the learning curve, and reduces the operating complexity, especially for beginner.

Hip survivorship following the Bernese periacetabular osteotomy for the treatment of acetabular dysplasia: A systematic review and meta-analysis

INTRODUCTION

The Bernese periacetabular osteotomy (PAO) is a popular joint-preservation technique aimed at addressing the structural and biomechanical abnormalities associated with acetabular dysplasia. However, the prognostic factors and long-term survivorship of the native hip, with failure defined as conversion to total hip arthroplasty (THA), is poorly understood. Our study aims to address the following: (1) What is the estimated duration of survival of the native hip post-PAO, (2) What are some prognostic factors of functional outcome and (3) What is the complication rate and complications associated with PAO.

HYPOTHESIS

The Bernese PAO is able to result in favourable mid- to long-term outcomes conditional on a stringent patient selection criteria.

MATERIALS AND METHODS

A systematic review was performed using the PRISMA guidelines. All studies that reported on the outcomes of isolated Bernese PAO for the treatment of acetabular dysplasia were included.

RESULTS

A total of 24 studies (3471 patients, 3655 hips) were included at a mean follow-up duration of 54.2months (range: 1-336months). In total, 208 hips (6.03%; 95% CI: 5.25-6.94%) converted to THA at a mean duration of 4.71years (range: 1-240months). Univariate analysis identified advanced age beyond a follow-up duration of 6years (p=0.001) and preoperative Tönnis grade 2 and above (p<0.001) to be the most significant negative prognostic factors. Beyond a follow-up duration of 2years, intraoperative fluoroscopy proved to be a significant positive prognostic factor (p<0.001). Indications for PAO, obesity and gender were not found to be significant predictors of failure. Our study found the complication rate to be 23.5% (95% CI: 21.6-25.6%). The most common complications detailed are transient lateral femoral cutaneous nerve dysesthesia (8.24%; 95% CI: 7.02-9.65%), stress fracture (5.28%; 95% CI: 4.31-6.89%) and the delayed union, non-union or pseudoarthrosis of the ramus not necessitating surgical correction (3.73%, 95% CI: 2.93-4.75%).

DISCUSSION

PAO alters the natural history of the dysplastic hip with a 10- and 20-year survivorship of approximately 75.9% and 36.5% of patients respectively. The ideal patient should be below 40years old, with a preoperative Tönnis grade of 0 or 1. Intraoperative fluoroscopy is able to guide a better precision when re-orientating the acetabulum.

LEVEL OF EVIDENCE

IV; systematic review and meta-analysis.

[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.

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.

Defining the Gothic Arch Angle (GAA) as a radiographic diagnostic tool for instability in hip dysplasia

In recent years, there has been a controversial discussion about whether borderline dysplastic hips should be treated with an arthroscopic procedure or rather with an acetabular reorientation. New research suggests that a classification into stable and unstable hips may be helpful. The aim of the study was to validate (1) the intra- and interobserver reliability of a newly defined radiographic parameter named the Gothic Arch Angle, (2) the association between the GAA and previously existing measurements used to define severity of acetabular dysplasia, and (3) the correlation between radiographic measurements of acetabular dysplasia with MRI findings previously suggestive of hip instability. We defined and validated the GAA in 10 standardized radiographs of asymptomatic hips by two observers and calculated intra- and interobserver coefficients at two individual dates. Subsequently, a consecutive series of 100 patients with dysplastic hips (LCEA < 25°, Toennis grade ≤ 1) were evaluated for signs of instability on anteroposterior (a.p.) pelvic radiographs and direct MR arthrography and were divided in two groups: stable and unstable. In these patients the LCEA, the AI, the FEAR index and the GAA were radiographically evaluated. Correlation analyses and a logistic regression analysis was performed to identify the predictive value of instability for each radiographic parameter. Cutoff probabilities analysis was performed using standard receiver operating characteristic (ROC) curves to rate the predictive efficiency value of the GAA. The GAA showed excellent inter- and intraobserver reliability. A correlation was found between GAA and FEAR index. A logistic regression analysis showed that LCEA, FEAR index and GAA are distinct predictors of instability in hip dysplasia. The GAA showed the largest area under the curve (AUC 0.96), indicating it to be the best predictor of instability with an optimal cutoff value of 90° (sensitivity, 0.95; specificity, 0.93). The GAA is a new available indicator for instability and is thus suggested to be used as a future radiographic parameter for the stability of dysplastic hips. Further studies are needed to understand how this parameter might additionally predict clinical outcome in the treatment of hip dysplasia.

Level of evidence: Level III, diagnostic study.

Is a periacetabular osteotomy as efficacious in retroversion as it is in dysplasia? : The role of femoral anteversion on outcome

Aims

Periacetabular osteotomy (PAO) is an established treatment for acetabular dysplasia. It has also been proposed as a treatment for patients with acetabular retroversion. By reviewing a large cohort, we aimed to test whether outcome is equivalent for both types of morphology and identify factors that influenced outcome.

Methods

A single-centre, retrospective cohort study was performed on patients with acetabular retroversion treated with PAO (n = 62 hips). Acetabular retroversion was diagnosed clinically and radiologically (presence of a crossover sign, posterior wall sign, lateral centre-edge angle (LCEA) between 20° and 35°). Outcomes were compared with a control group of patients undergoing PAO for dysplasia (LCEA < 20°; n = 86 hips). Femoral version was recorded. Patient-reported outcome measures (PROMs), complications, and reoperation rates were measured.

Results

The mean Non-Arthritic Hip Score (NAHS) preoperatively was 58.6 (SD 16.1) for the dysplastic hips and 52.5 (SD 12.7) for the retroverted hips (p = 0.145). Postoperatively, mean NAHS was 83.0 (SD 16.9) and 76.7 (SD 17.9) for dysplastic and retroverted hips respectively (p = 0.041). Difference between pre- and postoperative NAHS was slightly lower in the retroverted hips (18.3 (SD 22.1)) compared to the dysplastic hips (25.2 (SD 15.2); p = 0.230). At mean 3.5 years’ follow-up (SD 1.9), one hip needed a revision PAO and no hips were converted to total hip arthroplasty (THA) in the retroversion group. In the control group, six hips (7.0%) were revised to THA. No differences in complications (p = 0.106) or in reoperation rate (p = 0.087) were seen. Negative predictors of outcome for patients undergoing surgery for retroversion were female sex, obesity, hypermobility, and severely decreased femoral anteversion.

Conclusion

A PAO is an effective surgical intervention for acetabular retroversion and produces similar improvements when used to treat dysplasia. Femoral version should be routinely assessed in these patients and when extremely low (< 0°), as an additional procedure to address this abnormality may be necessary. Females with signs of hypermobility should also be consulted of the likely guarded improvement.

Cite this article: Bone Jt Open 2021;2(9):757–764.

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.

Periacetabular osteotomy vs. total hip arthroplasty in young active patients with dysplastic hip: Systematic review and meta-analysis

BACKGROUND

In young active patients with hip dysplasia, choosing between periacetabular osteotomy (PAO) and total hip arthroplasty (THA) is challenging.

MATERIALS AND METHODS

We systematically searched Medline, Embase, and Cochrane Library for studies published until October 10, 2019, comparing PAO and THA in patients with dysplastic hip. We compared postoperative complications' incidences, end-stage revisions, and clinical scores.

RESULTS

Five studies with 431 hips (PAO: 235; THA: 196) were included. The incidence of overall and major complications was not different between groups (PAO: OR 2.14; 95% CI, 0.58-7.96; p=0.26; follow-up, 4-7.8 years; THA: OR 2.56; 95% CI, 0.60-10.98; p=0.21; follow-up, 4-7.8 years). There was also no difference in end-stage revision (OR 0.95; 95% CI, 0.33-2.79; p=0.93; follow-up, 4-7.8 years). The standard mean of Western Ontario McMasters Universities (WOMAC) pain score was higher in the THA than in the PAO group (standardized mean difference [SMD] -0.57; 95% CI, -0.93--0.21; p=0.002; follow-up, 4-5.5 years); however, the WOMAC functional score did not differ significantly between groups (SMD -0.16; 95% CI, -1.29-0.97; p=0.78; follow-up, 4-5.5 years). The standard mean UCLA activity index was higher in the PAO than in the THA group (SMD 0.28; 95% CI, 0.02-0.53; p=0.03; follow-up, 5.9-7.3 years).

CONCLUSIONS

The incidence of postoperative complications and revision surgery was not different between THA and PAO groups. However, postoperative pain was less in the THA group and the activity score was higher in the PAO group in the follow-up periods.

LEVEL OF EVIDENCE

III; meta-analysis.

A minimally invasive periacetabular osteotomy technique: minimizing intraoperative risks

The periacetabular osteotomy (PAO) is an extensive surgical procedure associated with potential risk to the adjacent neurovascular structures. A steep learning curve exists, with surgeon experience an important factor in outcome. Little detail exists of the osteotomies themselves, and how to make them safe and reproducible. This article describes our PAO technique with emphasis on specific safety steps. When performing the posterior column cut, migration of the osteotome beyond the lateral pelvis may lead to damage of the sciatic nerve. The safety features detailed include novel measurement of the posterior column width and the use of specific-width osteotomes to complete this osteotomy. To plan the cut, several computerized tomography-based measurements are taken starting just above the greater sciatic notch and continuing down to the inferior part of the acetabulum. The angle of this cut is determined by acetabular morphology and the width of the posterior column. These posterior column width measurements will determine the width of the osteotomes used to perform the cut with little risk that an osteotome will penetrate too far on the lateral side of the pelvis. To ensure the lateral cortex has been cut completely proximally, an osteotome with pre-measured depths may be used from a medial to a direct lateral trajectory. The senior author has been performing this modified approach since 2010 (n = 530 PAOs) and has witnessed no vascular injuries and no nerve injuries aside from minor lateral femoral cutaneous nerve issues. Utilization of these techniques has prevented any major nerve injury without the need for intraoperative electromyography.

Hypermobility, age 40 years or older and BMI >30 kg m-2 increase the risk of complications following peri-acetabular osteotomy

The peri-acetabular osteotomy (PAO) is a powerful surgical procedure for correcting symptomatic acetabular dysplasia, but it carries the potential for significant surgical complications. This study aims to determine the complication profile of PAO in a series performed by an experienced single surgeon. This was as retrospective review of 223 hips in 200 patients (23 bilateral, 22 males and 201 females). Complication data were collected from notes and radiographic review and graded according to a modified Dindo–Clavien classification. Each hip could be recorded as having more than one complication. Mean age at surgery was 28.8 years (range 13-48), mean weight was 70.9 kg (range 45–115 kg). Diagnosis was dysplasia in 185 hips, retroversion in 25 and a combination in 13. Mean follow-up was 26 months. In all, 61.4% of hips (137) had no complications; 74.0% had no complications or a Grade I complication (one that did not change management); 52 hips (23%) required pharmaceutical interventions (Grade II complications). Six hips (2.7%) suffered a major complication (Grade III or IV) as a direct consequence of the PAO. There were no Grade V complications (death). Hypermobility (Beighton’s score of ≥6, Odds ratio (OR) 2.525 P = 0.041), age 40 years or older (OR 3.126 P = 0.012) and BMI >30 (OR 2.506 P = 0.031), but not Tonnis grade (P = 0.193) increased the risk of more severe complications following a PAO. This single surgeon series from a high volume centre demonstrates that age 40 years or older and BMI >30 kg m⁻² and hypermobility increase the risk of more severe of complications.

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.

Does hip preservation surgery prevent arthroplasty? Quantifying the rate of conversion to arthroplasty following hip preservation surgery

Hip arthroscopic surgery for femoroacetabular impingement and periacetabular osteotomy (PAO) for dysplasia is the most commonly used contemporary treatment for these conditions and has been shown to provide pain relief and restore function. What is less understood and perhaps of more interest to health economists, is the role of these procedures in preserving the hip joint and avoiding hip arthroplasty. The aim of this systematic review was to determine whether hip joint preservation surgery, indeed, preserves the hip joint by looking at conversion rates to total hip arthroplasty (THA). Two separate searches were undertaken, using PRISMA guidelines and utilizing PubMed and Open Athens search engines, identifying manuscripts that looked at conversion to THA following either hip arthroscopy (HA) or PAO. When considering HA, we found 64 eligible papers. Out of these studies, there were 59 430 hips with 5627 undergoing conversion to THA (9.47% [95% CI 9.23–9.71%]) with a mean conversion time of 24.42 months. Regarding PAO, there were 46 eligible papers including 4862 patients who underwent PAO with subsequent conversion to THA in 404 patients (8.31% [95% CI 7.54–9.12%]). with a mean conversion time of 70.11 months. Certain features were associated with increased conversion rates, including increasing age, worsening arthritis and joint space <2 mm. This study demonstrates that the mean conversion rates to be <10% for HA and PAO, during the mean follow-up periods of included manuscripts. Joint preserving surgery appears to defer or at least delay the need for THA.

Spinopelvic Characteristics in Acetabular Retroversion: Does Pelvic Tilt Change After Periacetabular Osteotomy?

BACKGROUND

Acetabular retroversion may lead to impingement and pain, which can be treated with an anteverting periacetabular osteotomy (aPAO). Pelvic tilt influences acetabular orientation; as pelvic tilt angle reduces, acetabular version reduces. Thus, acetabular retroversion may be a deformity secondary to abnormal pelvic tilt (functional retroversion) or an anatomic deformity of the acetabulum and the innominate bone (pelvic ring).

PURPOSE

To (1) measure the spinopelvic morphology in patients with acetabular retroversion and (2) assess whether pelvic tilt changes after successful anteverting PAO (aPAO), thus testing whether preoperative pelvic tilt was compensatory.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A consecutive cohort of 48 hips (42 patients; 30 ± 7 years [mean ± SD]) with acetabular retroversion that underwent successful aPAO was studied. Spinopelvic morphology (pelvic tilt, pelvic incidence, anterior pelvic plane, and sacral slope) was measured from computed tomography scans including the sacral end plate in 21 patients, with adequate images. In addition, the change in pelvic tilt with aPAO was measured via the sacrofemoral-pubic angle with supine pelvic radiographs at an interval of 2.5 ± 2 years.

RESULTS

The spinopelvic characteristics included a pelvic tilt of 4° ± 4°, a sacral slope of 39° ± 9°, an anterior pelvic plane angle of 11° ± 5°, and a pelvic incidence of 42° ± 10°. Preoperative pelvic tilt was 4° ± 4° and did not change postoperatively (4° ± 4°) (P = .676).

CONCLUSION

Pelvic tilt in acetabular retroversion was within normal parameters, illustrating "normal" sagittal pelvic balance and values similar to those reported in the literature in healthy subjects. In addition, it did not change after aPAO. Thus, acetabular retroversion was not secondary to a maladaptive pelvic tilt (functional retroversion). Further work is required to assess whether retroversion is a reflection of a pelvic morphological abnormality rather than an isolated acetabular abnormality. Treatment of acetabular retroversion should focus on correcting the deformity rather than attempting to change the functional pelvic position.

Cartilage Quality (dGEMRIC Index) Following Knee Joint Distraction or High Tibial Osteotomy

OBJECTIVE

High tibial osteotomy (HTO) and knee joint distraction (KJD) are treatments to unload the osteoarthritic (OA) joint with proven success in postponing a total knee arthroplasty (TKA). While both treatments demonstrate joint repair, there is limited information about the quality of the regenerated tissue. Therefore, the change in quality of the repaired cartilaginous tissue after KJD and HTO was studied using delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC).

DESIGN

Forty patients (20 KJD and 20 HTO), treated for medial tibiofemoral OA, were included in this study. Radiographic outcomes, clinical characteristics, and cartilage quality were evaluated at baseline, and at 1- and 2-year follow-up.

RESULTS

Two years after KJD treatment, clear clinical improvement was observed. Moreover, a statistically significant increased medial (Δ 0.99 mm), minimal (Δ 1.04 mm), and mean (Δ 0.68 mm) radiographic joint space width (JSW) was demonstrated. Likewise, medial (Δ 1.03 mm), minimal (Δ 0.72 mm), and mean (Δ 0.46 mm) JSW were statistically significantly increased on radiographs after HTO. There was on average no statistically significant change in dGEMRIC indices over two years and no difference between treatments. Yet there seemed to be a clinically relevant, positive relation between increase in cartilage quality and patients' experienced clinical benefit.

CONCLUSIONS

Treatment of knee OA by either HTO or KJD leads to clinical benefit, and an increase in cartilage thickness on weightbearing radiographs for over 2 years posttreatment. This cartilaginous tissue was on average not different from baseline, as determined by dGEMRIC, whereas changes in quality at the individual level correlated with clinical benefit.

Complications and outcome after periacetabular osteotomy - influence of surgical approach

BACKGROUND

Bernese periacetabular osteotomy (PAO) was introduced by Ganz as a novel surgical technique for hip dysplasia with a congruent hip to reorient the acetabulum in skeletally mature patients. The PAO through a modified Smith-Petersen (Iliofemoral) approach, has been subject to many modifications in order to avoid complications and to minimise risks for failure.

AIM

The aim of this review was to report on the complication rates, functional and radiological outcomes in relation to surgical approaches.

METHODS

A search of NICE healthcare database advanced search, was conducted from the year of inception to May 2018. We included studies that reported complications of PAO. Data extracted from case series was analysed to detect the incidence of complications, relation to surgical approach and temporal trend of complications.

RESULTS

40 studies including 4070 hips with a mean age of 29 years and a mean follow-up of 52.8 month, were analysed. Outcome measures demonstrated good to excellent outcome in 82%. Higher rates of LFCN and sciatic nerve injuries were found to be associated with the ilioinguinal and the 2-incision approach. Minimally invasive (MIS) modified Smith-Petersen (MSP), minimally invasive trans-sartorial and trans-trochanteric approaches were not reported to be associated with any major wound complications. Radiological correction achieved with a mean improvement in acetabular inclination of 17.90 (range 4.5-40), anterior centre-edge correction 25.40 (range 10-51), lateral centre-edge correction 23.30 (range 15-44.6) and medial translation of 6 mm (range 3.2-10).

CONCLUSIONS

The complication rates seem to be lower in this current review (7%) as compared to the previous review performed by Clohisy et al. (6-37%). The MIS trans-sartorial/MIS MSP and intertrochanteric approaches are associated with an even reduced complications rates. This review enables favouring the minimally invasive approaches with regard to reducing nerve injury and wound complications.

Modified iliac spine wafer osteotomy for exposure during Bernese periacetabular osteotomy

The Bernese periacetabular osteotomy (PAO) is a well-established procedure for the management of symptomatic hip dysplasia. The associated Smith–Petersen exposure offers excellent visualization of the acetabulum and control of acetabular osteotomy and mobilization. The traditional exposure of the true pelvis involves osteotomy of the iliac wing in order to mobilize the sartorial and inguinal ligament insertion. However, full osteotomy of the iliac spine may necessitate screw fixation if a relatively large segment of bone is included. A known complication with screw fixation of the iliac wing osteotomy involves failure of fixation and screw back out. Moreover, the screw may irritate the patient even in the setting of adequate fixation. A larger osteotomy may also injure the lateral femoral cutaneous nerve (LFCN) as it travels near the anterior–superior spine. To minimize the risk of these potential complications, a wafer osteotomy may be used to develop a sleeve of tissue involving the sartorial insertion. This sleeve also mobilizes the entirety of the LFCN medially and affords protection throughout the procedure. Furthermore, the wafer osteotomy may be re-fixed to the stable pelvis during closure with simple heavy suture fixation alone, avoiding screw insertion or associated removal. Because only a wafer or bone is taken during the spine osteotomy, more bone is available at the anterior–superior iliac spine for fixation of the mobile fragment after repositioning. In this technical note, we describe the wafer osteotomy technique in further detail.

The CU PAO: A Minimally Invasive, 2-Incision, Interlocking Periacetabular Osteotomy: Technique and Early Results

BACKGROUND

The aims of this study were to describe a novel minimally invasive, interlocking periacetabular osteotomy (PAO) for the treatment of hip dysplasia that was developed at our institution and to report on its safety, complications, and early clinical outcomes.

METHODS

This was a prospective longitudinal study of the first 200 consecutive hips that underwent the CU (University of Colorado) PAO, an interlocking osteotomy combining the benefits of the Birmingham interlocking pelvic osteotomy (BIPO) and the Ganz PAO. The technique provides direct visualization of the sciatic nerve during the ischial osteotomy and allows for immediate weight-bearing postoperatively. Demographic characteristics, intraoperative and perioperative parameters, and functional outcomes were documented. All patients underwent hip arthroscopy 3 to 10 days prior to the PAO to address concomitant intra-articular pathology. Mechanical deep venous thrombosis (DVT) prophylaxis was used for 2 weeks postoperatively. Results were stratified to compare the first 100 and the second 100 cases.

RESULTS

A total of 161 patients (200 hips) underwent primary PAO; mean follow-up was 20 months (range, 3 to 33 months). The mean patient age at the time of surgery was 29.4 years (range, 13 to 55 years). Females accounted for 89% of the patients included in this study. The average length of stay was 4 days. A concomitant proximal femoral derotational osteotomy was performed in 19 hips. The lateral center-edge angle (LCEA) improved from a mean of 18.8° preoperatively to 31.5° postoperatively (p < 0.001). The mean Non-Arthritic Hip Score (NAHS) improved from 56.0 preoperatively to 89.4 at the 24-month follow-up (p < 0.0001). Paresthesias in the distribution of the lateral femoral cutaneous nerve were common (65% at 2 weeks postoperatively) but resolved in 85% of the patients within the first 6 months. There were no sciatic nerve-related complications, deep infections, or DVTs.

CONCLUSIONS

The CU PAO enables corrective realignment of symptomatic acetabular dysplasia with direct visualization of the sciatic nerve, early weight-bearing, cosmetic incisions, and good short-term outcomes.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

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.

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.

[Development of hip preservation in treating adult hip dysplasia]

During the past decades, the field of hip preservation in China has achieved great improvements. Theoretically, the blood supply of the femoral head and the acetabulum along with the mechanism of early-stage hip osteoarthritis has been gradually cleared. The knowledge and application of the periacetabular osteotomy, surgical hip dislocation, and hip arthroscopy has been vigorously promoted. Improved understanding of the mechanism, pathology, and prevention protocols of the secondary hip dysplasia have been obtained, despite the fact that lack of awareness of some mechanism and detail, for example, hip instability or borderline dysplasia, etc. On the basis of summing up those clinical progress, this article further elaborated the historical development of hip preservation through the review of several traditional treatment, and made objective assessment about the follow-up, evaluation, minimally invasive surgery, and individualized treatment newly reported.

The management of the painful borderline dysplastic hip

Improved imaging and the evolution of surgical techniques have permitted a rapid growth in hip preservation surgery over the last few decades. The management of the painful borderline dysplastic hip however remains controversial. In this review, we will identify the pertinent issues and describe the patient assessment and treatment options. We will provide our own recommendations and also identify future areas for research.

A Traffic Light Grading System of Hip Dysplasia to Predict the Success of Arthroscopic Hip Surgery

BACKGROUND

The role of hip arthroscopic surgery in dysplasia is controversial.

PURPOSE

To determine the 7-year joint preservation rate after hip arthroscopic surgery in hip dysplasia and identify anatomic and intraoperative features that predict the success of hip preservation with arthroscopic surgery, allowing the formulation of an evidence-based classification system.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Between 2008 and 2013, 111 hips with dysplastic features (acetabular index [AI] >10° and/or lateral center-edge angle [LCEA] <25°) that underwent arthroscopic surgery were identified. Clinical, radiological, and operative findings and the type of procedure performed were reviewed. Radiographic evaluations of the operated hip (AI, LCEA, extrusion index) were performed. Outcome measures included whether the hip was preserved (ie, did not require arthroplasty) at follow-up and the preoperative and postoperative Non-Arthritic Hip Score (NAHS) and Hip disability and Osteoarthritis Outcome Score (HOOS). The AI and LCEA were calculated, factored by a measure of articular wear (AI_f and LCEA_f, respectively), according to the University College Hospital, London (UCL) grading system as follows: AI_f = AI × (number of UCL wear zones + 1), and LCEA_f = LCEA / (number of UCL wear zones + 1). A contour plot of the resulting probability value of failure for every combination of AI_f and LCEA_f allowed for the determination of the zones with the lowest and highest incidences of failure to preserve the hip.

RESULTS

The mean AI and LCEA were 9.8° and 18.0°, respectively. At a mean follow-up of 4.5 years (range, 0.4-8.3 years), 33 hips had failed, requiring hip arthroplasty. The 7-year joint survival rate was 68%. The mean improvements in the NAHS and HOOS were 11 ( P = .001) and 22.8 ( P < .001) points, respectively. The zone with the greatest chance of joint preservation (odds ratio, 10; P < .001) was the green zone, with an AI_f of 0° to 15° and an LCEA_f of 15° to 25°; in contrast, the zone with the greatest chance of failure (odds ratio, 10; P < .001) was the red zone, with an AI_f of 20° to 100° and an LCEA_f of 0° to 10°.

CONCLUSION

Overall, the 7-year hip survival rate in hip dysplasia appears inferior compared with that reported in femoroacetabular impingement (78%). Hip arthroscopic surgery is associated with an excellent chance of hip preservation in mild dysplasia (green zone: AI = 0°-15°, LCEA = 15°-25°) and no articular wear. The authors advise that the greatest caution should be used when considering arthroscopic options in cases of severe dysplasia (red zone: AI >20° and/or LCEA <10°).