Microinstability of the hip: a previously unrecognized pathology

Factors influencing patient-reported outcomes following periacetabular osteotomy and open osteochondroplasty in the setting of borderline hip dysplasia

Aims

This study reports mid-term outcomes after periacetabular osteotomy (PAO) exclusively in a borderline hip dysplasia (BHD) population to provide a contrast to published outcomes for arthroscopic surgery of the hip in BHD.

Methods

We identified 42 hips in 40 patients treated between January 2009 and January 2016 with BHD defined as a lateral centre-edge angle (LCEA) of ≥ 18° but < 25°. A minimum five-year follow-up was available. Patient-reported outcomes (PROMs) including Tegner score, subjective hip value (SHV), modified Harris Hip Score (mHHS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were assessed. The following morphological parameters were evaluated: LCEA, acetabular index (AI), α angle, Tönnis staging, acetabular retroversion, femoral version, femoroepiphyseal acetabular roof index (FEAR), iliocapsularis to rectus femoris ratio (IC/RF), and labral and ligamentum teres (LT) pathology.

Results

The mean follow-up was 96 months (67 to 139). The SHV, mHHS, WOMAC, and Tegner scores significantly improved (p < 0.001) at last follow-up. According to SHV and mHHS, there were three hips (7%) with poor results (SHV < 70), three (7%) with a fair score (70 to 79), eight (19%) with good results (80 to 89), and 28 (67%) who scored excellent (> 90) at the last follow-up. There were 11 subsequent operations: nine implant removals due to local irritation, one resection of postoperative heterotopic ossification, and one hip arthroscopy for intra-articular adhesions. No hips were converted to total hip arthroplasty at last follow-up. The presence of preoperative labral lesions or LT lesions did not influence any PROMs at last follow-up. From the three hips that had poor PROMs, two have developed severe osteoarthritis (> Tönnis II), presumably due to surgical overcorrection (postoperative AI < -10°).

Conclusion

PAO is reliable in treating BHD with favourable mid-term outcomes. Concomitant LT and labral lesions did not negatively influence outcomes in our cohort. Technical accuracy with avoidance of overcorrection is essential in achieving successful outcomes.

Treatment of Hip Microinstability with Arthroscopic Capsular Plication: A Retrospective Case Series

Purpose

Hip microinstability is defined as hip pain with a snapping and/or blocking sensation accompanied by fine anatomical anomalies. Arthroscopic capsular plication has been proposed as a treatment modality for patients without major anatomic anomalies and after failure of properly administered conservative treatment. The purpose of this study was to determine the efficacy of this procedure and to evaluate potential predictors of poor outcome.

Materials and Methods

A review of 26 capsular plications in 25 patients was conducted. The mean postoperative follow-up period for the remaining patients was 29 months. Analysis of data included demographic, radiological, and interventional data. Calculation of pre- and postoperative WOMAC (Western Ontario and McMaster Universities Osteoarthritis) index was performed. Pre- and postoperative sports activities and satisfaction were also documented. A P<0.05 was considered significant.

Results

No major complications were identified in this series. The mean pre- and postoperative WOMAC scores were 62.6 and 24.2, respectively. The WOMAC index showed statistically significant postoperative improvement (P=0.0009). The mean satisfaction rate was 7.7/10. Four patients with persistent pain underwent a periacetabular osteotomy. A lateral center edge angle ≤21° was detected in all hips at presentation. We were not able to demonstrate any difference in postoperative evolution with regard to the presence of hip dysplasia (P>0.05), probably because the sample size was too small.

Conclusion

Capsular plication can result in significant clinical and functional improvement in carefully selected cases of hip microinstability.

Generalized Joint Laxity Is Associated With Dynamic Hip Ultrasonography Measures in Female Athlete Patients Who Are Not Hypermobile

OBJECTIVES

To investigate ultrasound (US) femoroacetabular translation measurements in female athlete patients.

METHODS

A prospective cross-sectional study was conducted in female athlete patients <50 years. Demographic data, Beighton score/hypermobility status, and sport participation were collected. Hip dysplasia was determined using radiographic measurements (lateral center edge angle, anterior center edge angle, Tönnis angle); femoral version angles were measured with CT or MR. Femoroacetabular translation US measures included neutral (N), neutral flexed (NF), extension external rotation/apprehension (EER) positions. Maximal difference (delta) between US measures was calculated.

RESULTS

206/349 female hips were analyzed (median age 21.2 years [range, 12-49.5]). The primary sport group was performing arts (45%, 92/206). Mean Beighton score was 5.2 (SD, 2.5) with 61% (129/206) of hips exhibiting hypermobility (Beighton score ≥5). For each additional unit of Beighton score, N US measurement increased by 0.7 mm (β = 0.7; 95% confidence interval [CI] = 0.22-1.25; P < .001), NF by 1 mm ( β = 0.9; 95% CI = 0.3-1.43; P = .002) and EER by 0.8 mm ( β = 0.8; 95% CI = 0.27-1.37; P < .001) when adjusting for age and dysplasia status. A positive correlation was detected between NF (r = 0.19; 95% CI = 0.05-0.33; P = .007) and EER (r = 0.19; 95% CI = 0.05-0.32; P = .01) with Tönnis angle and a negative correlation between the delta and femoral version (r = -0.20; 95% CI = -0.35 to 0.03; P = .02). No difference in US measures was detected across sport groups (N [P = .24], NF [P = .51], EER [P = .20], delta [P = .07]).

CONCLUSION

Beighton score was independently associated with dynamic US measures in female athlete patients who are not hypermobile when controlling for other factors.

Does Femoral Head Translation Vary by Sex and Side in Asymptomatic Hips During a Weightbearing Apprehension Test?

BACKGROUND

Hip microinstability is an increasingly recognized source of pain and dysfunction but has no agreed upon diagnostic criteria and the pathophysiology remains unclear. It has been suggested that pain associated with microinstability is caused by excess translation of the femoral head. Recent research indicates that single-plane femoral head translation can be reliably measured using dynamic ultrasonography during a supine clinical examination; however, the overall accuracy of that technique has not been established, and the range of femoral head translation values that are found in individuals with no history of surgery or symptomatic pathology is unknown.

QUESTIONS/PURPOSES

(1) How much femoral head translation is present in native, uninjured hips during a weightbearing apprehension position for females and males? (2) How large is the side-to-side difference in hip translation and rotation within the same individual in females and males with no history of surgery or pain during the weightbearing apprehension position? (3) What differences exist in femoral head translation and rotation when comparing females to males?

METHODS

Twenty-two young adults (11 males, 11 females; mean age 22 ± 2 years; BMI 22 ± 5 kg/m2) with no history of hip pain, no known hip injury, and who never had hip surgery participated in this study. High-resolution CT images of the femur and pelvis were acquired for each participant, and the bone tissue was segmented from the CT volume. Synchronized biplane radiographs were collected during a neutral standing trial and during a static weightbearing apprehension position in which the participant extended, externally rotated, and abducted at their back hip while standing with their feet split in the AP direction. A validated volumetric model-based tracking technique was used to match the patient-specific bone models to the biplane radiographs with an accuracy of 0.3 mm for translation and 0.8° for rotation. Translation of the center of the femoral head relative to the center of the acetabulum and rotation of the femur relative to the pelvis from neutral to the weightbearing apprehension position were calculated. Sex-based differences in hip kinematics were assessed by bivariate linear regression.

RESULTS

The median (range) translation during the weightbearing apprehension position in females was 0.9 mm (0.2 to 2.7 mm), which was less than in the 1.3 mm (0.2 to 2.6 mm) translation found in males (median difference of 0.5 mm; p = 0.04). The median absolute side-to-side difference in translation during the pivot was 1.4 mm (0.1 to 3.8 mm) in females and 1.3 mm (0.1 to 4.4 mm) in males.

CONCLUSION

These findings demonstrate that the femoral head translates the same under bodyweight loading as previously observed during supine exam, showing the inherent stability of the hip with no history of surgery or symptomatic pathology. This study also provides normal values for comparison with individuals who have suspected microinstability. Future directions for research include directly comparing biplane radiography to alternative imaging techniques, such as dynamic ultrasound, for identifying hip microinstability and identifying threshold values for symptomatic hip microinstability.

LEVEL OF EVIDENCE

Level III, prognostic study.

Nonarthritic Hip Pathology Patterns According to Sex, Femoroacetabular Impingement Morphology, and Generalized Ligamentous Laxity

BACKGROUND

Sex differences are frequently encountered when diagnosing orthopaedic problems. Current literature suggests specific sex differences, such as a higher prevalence of cam-type femoroacetabular impingement syndrome in male patients and features of hip instability in female patients.

PURPOSE

To identify hip pathology patterns according to sex, alpha angle deformity, and generalized ligamentous laxity (GLL) in a nonarthritic patient population that underwent primary hip arthroscopy in the setting of femoroacetabular impingement syndrome and labral tears.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Patients who underwent primary hip arthroscopy between February 2008 and February 2017 were included and separated into male and female groups for initial analysis. Patients were excluded if they had Tönnis osteoarthritis grade >1, previous ipsilateral hip surgery, or previous hip conditions. The demographics, radiographic findings, intraoperative findings, and surgical procedures were then analyzed and compared. Subanalyses were performed for both groups. A threshold of 1 SD above the mean alpha angle in the male group was used to create 2 subgroups. For female patients, GLL based on a Beighton score ≥4 was used to divide the group. Intraoperative findings were compared for both subanalyses.

RESULTS

A total of 2701 hips met all inclusion and exclusion criteria. Of those, 994 hips were in the male group and 1707 in the female group. The mean ± SD age was 36.6 ± 13.8 and 37.1 ± 15.0 years for the male and female groups, respectively(P = .6288). The average body mass index was significantly higher in the male group (P < .0001). GLL was more common in women (38.6%) than men (13.6%) (P < .001). The male group had a higher proportion of acetabular Outerbridge grade 3 (21.8%) and 4 (19.2%) lesions when compared with the female group (9.3% and 6.3%, respectively) (P < .0001). Men in the subgroup with an alpha angle ≥78° reported higher rates of acetabular Outerbridge grade 4 damage than men with an alpha angle <78° (P < .001). Mean lateral center-edge angle was lower in the female subgroup with Beighton score ≥4 vs <4 (23.7°± 4.2° vs 31.3°± 5.8°; P < .0001).

CONCLUSION

In this analysis of a large cohort of patients who underwent hip arthroscopy, 2 patterns of hip pathologies were related to sex. On average, male patients had larger alpha angles and increased acetabular chondral damage when compared with their female counterparts. Furthermore, a larger cam-type anatomy was associated with more severe acetabular chondral damage in men. In the female group, the incidence of features of hip instability such as GLL were significantly higher than in the male group.

Comprehensive analysis of pathological changes in hip joint capsule of patients with developmental dysplasia of the hip

Aims

Developmental dysplasia of the hip (DDH) is a complex musculoskeletal disease that occurs mostly in children. This study aimed to investigate the molecular changes in the hip joint capsule of patients with DDH.

Methods

High-throughput sequencing was used to identify genes that were differentially expressed in hip joint capsules between healthy controls and DDH patients. Biological assays including cell cycle, viability, apoptosis, immunofluorescence, reverse transcription polymerase chain reaction (RT-PCR), and western blotting were performed to determine the roles of the differentially expressed genes in DDH pathology.

Results

More than 1,000 genes were differentially expressed in hip joint capsules between healthy controls and DDH. Both gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that extracellular matrix (ECM) modifications, muscle system processes, and cell proliferation were markedly influenced by the differentially expressed genes. Expression of Collagen Type I Alpha 1 Chain (COL1A1), COL3A1, matrix metalloproteinase-1 (MMP1), MMP3, MMP9, and MMP13 was downregulated in DDH, with the loss of collagen fibres in the joint capsule. Expression of transforming growth factor beta 1 (TGF-β1) was downregulated, while that of TGF-β2, Mothers against decapentaplegic homolog 3 (SMAD3), and WNT11 were upregulated in DDH, and alpha smooth muscle actin (αSMA), a key myofibroblast marker, showed marginal increase. In vitro studies showed that fibroblast proliferation was suppressed in DDH, which was associated with cell cycle arrest in G0/G1 and G2/M phases. Cell cycle regulators including Cyclin B1 (CCNB1), Cyclin E2 (CCNE2), Cyclin A2 (CCNA2), Cyclin-dependent kinase 1 (CDK1), E2F1, cell division cycle 6 (CDC6), and CDC7 were downregulated in DDH.

Conclusion

DDH is associated with the loss of collagen fibres and fibroblasts, which may cause loose joint capsule formation. However, the degree of differentiation of fibroblasts to myofibroblasts needs further study.

Cite this article: Bone Joint Res 2021;10(9):558–570.

Hip arthroscopy and T-shaped capsular plication for the treatment of borderline dysplasia: a minimum 2-year follow-up

PURPOSE

The aim of the study was to evaluate the clinical outcomes of patients treated arthroscopically for symptomatic borderline dysplasia of the hip (BHD) with a T-shaped capsular plication, with a minimum follow-up of 24 months.

METHODS

Twenty-seven patients who had undergone hip arthroscopy and T-shaped capsular plication for symptomatic BHD were included in the study. All patients were clinically evaluated prior to surgery (T₀) and at two consecutive follow-ups (T₁: 12 ± 1.2 months; T₂: 52.0 ± 23.2 months) using the visual analogue scale (VAS) pain score, the Hip Outcome Score in activities of daily living (HOS-ADL) and sport-specific subscale (HOS-SSS), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Short Form-12 in its physical (PCS) and mental component scores (MCS). We also evaluated the presence of correlations and analysed the possible differences between subgroups.

RESULTS

We found a significant difference for HOS-ADL, HOS-SSS, VAS and WOMAC with the Friedman test for repeated measures through time points (p < 0.0001), but not for MCS. All clinical scores reported a significant improvement compared to the previous time point (p < 0.05), with the exception of HOS-SSS, for which p = 0.2570 between T₁ and T₂. The body mass index was positively correlated with preoperative VAS (R = 0.42857; p = 0.0257) and negatively correlated with PCS at T₀ (R = - 0.40999; p = 0.0337) and with PCS (R = - 0.40491; p = 0.0362), MCS (R = - 0.45939; p = 0.0159) and WOMAC (R = - 0.40573; p = 0.0216) at T₂. No complications were reported in our cohort.

CONCLUSIONS

The results of the current study confirm that patients with intra-articular hip pathology and concomitant BHD (LCEA 20°-25°) can benefit from arthroscopic treatment and that T-shaped capsular plication is one of the available options. Orthopaedic surgeons specialising in hip arthroscopy should consider arthroscopy for the treatment of symptomatic BHD for stabilising and strengthening the joint. Future studies should focus on finding out which type of patients can benefit most from this procedure.

LEVEL OF EVIDENCE IV

Prospective Case Series.

Hypermobile Disorders and Their Effects on the Hip Joint

Hypermobility, or joint hyperlaxity, can result from inherited connective tissue disorders or from micro- or macrotrauma to a joint. The supraphysiologic motion of the hip joint results in capsuloligamentous damage, and these patients have a propensity to develop femoroacetabular impingement syndrome (FAIS) and labral injury. In this review, the recent literature evaluating the definitions, history, incidence, genetics, and histology of hypermobile disorders is investigated. We then review the clinical evaluation, natural history, and resulting instability for patients presenting with a hypermobile hip. Lastly, treatment options and outcomes will be highlighted.

Comparison of postoperative effectiveness of less invasive short external rotator sparing approach versus standard posterior approach for total hip arthroplasty

Background

Most of the studies assessing the corrective posterior total hip arthroplasty (THA) mainly focused on the mini-incision approach. Studies exploring the short external rotator sparing approach are rare. Therefore, this study aimed to compare the effectiveness of standard posterior approach and short external rotator sparing approach.

Methods

This prospective observational study included 126 patients who underwent THA in June 2017–June 2018. Patients were assigned to standard (standard posterior approach) and corrective (short external rotator sparing approach) groups based on the surgical method. Surgical data were recorded postoperatively. Postoperative hip joint recovery was assessed using the times to ambulation and independent stair use, and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, Harris score, and Oxford hip score (OHS) at 2 and 8 postoperative weeks. The visual analog scale (VAS) was used for postoperative pain assessment.

Results

Postoperative changes of creatine kinase (CK), myoglobin, CRP, and prosthesis position were similar in both groups (P > 0.05). However, intraoperative blood loss (P < 0.001) and postoperative 6-h drainage volume (P = 0.03), hospital stay, blood transfusion rate, and times to ambulation and independent stair use were significantly reduced in the corrective group. Postoperatively, Oxford, and WOMAC scores significantly decreased in both groups. After surgery, the VAS score was more overtly decreased in the corrective group compared with the standard group.

Conclusions

This study concluded that the less invasive short external rotator sparing approach for THA caused less damage, reducing perioperative blood loss, shortening functional recovery time, maintaining prosthesis stability, and improving postoperative pain.

Biomechanical evaluation of a hybrid suture and anchor-based hip capsular repair

BACKGROUND

Hip capsulotomies, performed routinely during hip arthroscopy, can contribute to adverse joint kinematics. Direct repair is not always feasible. Therefore, the aim of this study was to evaluate the biomechanics of a conventional all-suture repair versus a hybrid suture and anchor-based capsular repair.

METHODS

Nine paired (n = 18) hips were tested on a joint-motion simulator, utilizing optical trackers to capture kinematic data. Pairs were randomly allocated to capsular repair type and tested as (1) intact, (2) after T-capsulotomy, and (3) repair each at 0°, 45°, and 90° flexion. Internal and external rotation torques and abduction/adduction torques of 3 N·m were applied and rotational range of motion and joint translations recorded.

FINDINGS

At 0°, following repair there were no significant differences in joint rotation or translations between repairs (p > 0.134). At 45°, both repair types restored motion to near intact values, with no significant differences between groups. Similarly, there were no significant differences in joint translations between repairs. At 90°, both types of capsular repair failed to restore rotational range of motion, with persistent increases in motion (47.0 ± 16.7°) compared to the intact condition (44.1 ± 15.8°, p = 0.006); however, there were no significant differences between repair groups. There were no significant differences in joint translations between repairs.

INTERPRETATION

Use of a hybrid repair produced comparable joint rotation and translation under all testing conditions as an all-suture repair. As such, this technique represents a viable option for capsular repair where proximal capsular tissue is deficient.

Mid-Term Outcomes of Combined Hip Arthroscopy and Limited Open Capsular Plication in the Non-Dysplastic Hip

BACKGROUND

Hip microinstability remains poorly-defined but increasingly diagnosed in the setting of borderline dysplasia (LCEA 20-25°), soft tissue laxity, or following unrepaired arthroscopic capsulotomy. While hip microinstability is com-monly treated with arthroscopic capsular plication with short-term outcomes reported, this procedure has been performed open for some time. The purpose of current study was to assess the durability of outcomes of combined arthroscopy and open capsular plication in treating symptomatic hip microinstability at mid-term follow-up.

METHODS

We retrospectively identified hips that underwent combined hip arthroscopy and open capsular plication for symptomatic microinstability between 2008 and 2013. Hips with excessive femoral anteversion (femoral version >35°) or classic acetabular dysplasia (LCEA <20°) were treated with bony reorientation and were not included in the current study. Patient reported outcomes scores were collected preoperatively and at a minimum five year follow-up. Hips that required reoperation or did not meet criteria for minimally clinically important difference (MCID, ≥8 increase in mHHS) or patient acceptable symptom scores (PASS, mHHS) were considered failures.

RESULTS

A total of 27 hips met criteria for inclusion and follow-up was obtained for 22 hips (81.5%) at a mean of 7.1 years. All patients were female with a mean age of 25.9 years and 7 (32%) hips had previous surgery. Patients undergoing the combined procedure improved from a mean baseline mHHS of 55.3±13 to a mean follow-up mHHS of 74.5±20.9 (p<0.001). At midterm follow-up, 54.5% of hips met criteria for PASS and 68.2% of hips met criteria for MCID, with 72.7% of hips meeting criteria for either MCID or PASS. Overall, 10 hips (45%) were considered failures with 6 hips (27%) requiring reoperation and an additional 4 hips (18%) with clinical failure. Hips without previous surgery had a failure rate of 33.3% (5/15) while 71.4% (5/7) of those with previous surgery failed (P=.09).

CONCLUSION

Our study demonstrates a high (45%) rate of reoperations and persistent symptoms in hips with microinstability treated with combined arthroscopy and open capsular plication. Further mid- and long-term studies evaluating soft tissue plication are needed, as well as comparisons with bony procedures in the setting of microinstability are needed.Level of Evidence: III.

Treatment type may influence degree of post-dislocation shoulder osteoarthritis: a systematic review and meta-analysis

PURPOSE

Age at primary dislocation, recurrence, and glenoid bone loss are associated with development of osteoarthritis (OA). However, an overview of OA following traumatic anterior shoulder instability is lacking and it is unclear to what degree type of surgery is associated with development of OA in comparison to non-operative treatment. The aim of this study was to determine the degree of OA at long-term follow-up after non-operative and operative treatments for patients with anterior shoulder instability. Surgery is indicated when patients experience recurrence and this is associated with OA; therefore, it was hypothesized that shoulders show a higher proportion or degree of OA following operative treatment compared to non-operative treatment.

METHODS

A literature search was performed in the PubMed/Medline, EMBASE, and Cochrane databases. Articles reporting the degree of OA that was assessed with the Samilson-Prieto or Buscayret OA classification method after non-operative and operative treatment for anterior shoulder instability with a minimum of 5 years follow-up were included.

RESULTS

Thirty-six articles met the eligibility criteria of which 1 reported the degree of OA for non-operative treatment and 35 reported the degree of OA for 9 different operative procedures. A total of 1832 patients (1854 shoulders) were included. OA proportions of non-operative and operative treatments are similar at any point of follow-up. The Latarjet procedure showed a lower degree of OA compared to non-operative treatment and the other operative procedures, except for the Bristow procedure and Rockwood capsular shift. The meta-analyses showed comparable development of OA over time among the treatment options. An increase in OA proportion was observed when comparing the injured to the contralateral shoulder. However, a difference between the operative subgroups was observed in neither analysis.

CONCLUSION

Non-operative and operative treatments show similar OA proportions at any point of follow-up. The hypothesis that shoulders showed a higher proportion or degree of OA following operative treatment compared to non-operative treatment is not supported by the data. Operative treatment according to the Latarjet procedure results in a lower degree of OA compared to other treatments, including non-operative treatment.

LEVEL OF EVIDENCE

IV.

Hip pain and its correlation with cam morphology in young skiers-a minimum of 5 years follow-up

BACKGROUND

There is conflicting evidence regarding the association between cam morphological changes and hip pain, and it remains unclear who with cam morphology will develop hip pain and who will not. This study aimed to investigate the correlation between cam morphology, hip pain, and activity level at a 5-year follow-up in young Alpine and Mogul skiers.

METHOD

All students (n = 76) at Åre Ski National Sports High School were invited and accepted participation in this prospective study at baseline. Magnetic resonance imaging (MRI) of both hips was conducted to evaluate the presence of cam morphology (α-angle ≥ 55°) and its size alongside the reporting of hip pain, type, and frequency of training by the Back and hip questionnaire, at baseline. After 5 years, the skiers were invited to complete a shortened version of the same questionnaire.

RESULTS

A total of 60 skiers (80%) completed the follow-up questionnaire, of which 53 had concomitant MRI data. Cam morphology was present in 25 skiers (47.2%, 39 hips). Hip pain at baseline and at follow-up was reported in 17 (28.3%) and 22 (36.7%) skiers, respectively. No correlations were found between the activity level, the frequency, and the size of cam morphology and hip pain, except for the right hip α-angle at 1 o'clock and hip pain in skiers with cam morphology at baseline (rs = 0.49; P = 0.03) and at follow-up (rs = 0.47; P = 0.04). A total of 73.3% skiers had retired, of which 48% reported this was due to injuries.

CONCLUSION

Hip pain was not shown to be correlated, or had a low correlation, with activity level and the presence and size of cam morphology in young skiers on a 5-year follow-up. Based on these results, cam morphology or activity level did not affect hip pain to develop during 5 years of follow-up in young skiers. Furthermore, this study highlights that almost 75% of young elite skiers had retired from their elite career with almost 50% reporting that this was due to injuries sustained from skiing.

Radiographic and clinical characteristics associated with a positive PART (Prone Apprehension Relocation Test): a new provocative exam to elicit hip instability

Hip instability due to mild dysplasia can be a diagnostic challenge. The physical exam is an important adjunct to radiographic evaluation for the clinical diagnosis of hip instability. Herein, we describe a new maneuver to replicate hip instability pain, called the PART (Prone Apprehension Relocation Test). We retrospectively identified patients in our institution’s hip preservation registry who presented for evaluation of hip pain. We divided patients into ‘positive’ or ‘negative’ PART and analyzed associated clinical and radiographic findings. Ninety patients (159 hips) were included, 83 female and 7 male, average age 27.3 ± 9.1 years. Thirty-four hips (21.4%) had a positive PART. There were no significant differences in hip range of motion, lateral center edge angle, or in acetabular depth. There was, however, a significant difference in acetabular version at 3 o’clock between the two test groups (18.5 ± 6.9° in negative, 21.2 ± 4.9° in positive, P = 0.045). There was no association between PART and previously described anterior apprehension testing. Historical methods of diagnosing hip dysplasia may not adequately identify patients with clinical hip instability. We describe a new provocative exam, the PART, which may be helpful in replicating hip instability symptoms in patients with anterior acetabular undercoverage. PART positive patients had significantly more acetabular anteversion at the 3 o’clock position, which is measured on computed tomography and is not visible on standard anteroposterior (AP) pelvis or false profile radiographs. We believe that the PART is a valuable supplement to clinical examination and radiographic measurements to identify patients with symptomatic hip instability.

Arthroscopic Hip Capsular Plication With Augmentation Using a Bioinductive Collagen Implant

With advancements in arthroscopic techniques and instrumentation, hip arthroscopy has become an increasingly used technique to treat soft-tissue and osseous pathologies about the hip. Patient predisposition to labral and capsular injuries can present as femoroacetabular impingement or hip dysplasia, sometimes in combination. Capsular management continues to be a topic of debate, with capsular repair becoming the standard of care in most cases. Furthermore, in cases of borderline dysplasia and microinstability, considerations for not only capsular repair but with plication has shown significant clinical success. Although plication in this setting has shown promise, given a 20% failure rate, we suggest capsular augmentation to bolster the repair. We present a technique of capsular augmentation using a bioinductive collagen implant (Smith & Nephew) to improve the capsular integrity following repair and plication. The benefits of this implant are easy delivery through standard arthroscopic portals and secure fixation to the capsular tissue. These implants have a proven track record in the shoulder and serve as a scaffold for improved tissue quality, and their application in hip arthroscopy has potential by increasing the integrity of the capsular repair. Future studies are needed to address the clinical outcomes of this technique.

The Pull Test: A Dynamic Test to Confirm Hip Microinstability

Purpose

To define a distraction distance (pull length) cut-off that would differentiate those patients with hip microinstability and those without the disorder, called the Pull-Out Test.

Methods

In total, 100 consecutive patients undergoing hip arthroscopy were included in the study. Patients were separated into a hip microinstability group (HMI) and non-hip microinstability group (NHI) based on the results of Beighton's score, the abduction–extension–external rotation test, hip extension–external rotation examination, and the prone instability test. Inclusion criteria were patients with an magnetic resonance imaging-proven labral tear who did not respond to conservative treatment and underwent hip arthroscopy. Exclusion criteria included those patients undergoing revision hip arthroscopy, had a previous surgery on the ipsilateral hip, or had severe arthritis in the hip. The Pull-Out Test was performed before surgery with the hip in 30° of abduction and the foot in 30° of external rotation. A blinded examiner places gross axial traction on the leg until a firm end point is reached. The distraction distance between the femoral head and acetabulum is the pull length.

Results

In total, 32 patients made up the HMI group whereas 68 patients were in the NHI group. The average pull length for the NHI group was 0.9 ± 0.1 cm and 1.7 ± 0.4 cm for the HMI group (P < .001). Subtracting the standard deviation from the HMI group average, when defined a cut off for hip microinstability as 1.3 cm. Using this value, we found the Pull-Out Test to have a sensitivity of 0.91 and specificity of 0.96. The positive predictive value for the Pull Test was 0.91 and the negative predictive value 0.97.

Conclusions

The Pull-Out Test is a useful test in identifying and confirming the presence of hip microinstability in patients undergoing hip arthroscopy. A pull-length of 1.3 cm or greater is consistent with the presence of microinstability with a specificity of 94% and a sensitivity of 96%.

Level of Evidence

Level IV, diagnostic, case-control study.

Exploring the role of microinstability of the hip: an atypical presentation of femoroacetabular impingement (FAI) and labral tear in a collegiate endurance athlete: a case report

OBJECTIVE

This case is designed to aid practitioners in understanding the potential role of hip microinstability as a possible underlying source of hip pain and dysfunction.

CASE PRESENTATION

A 25-year-old female collegiate cross-country athlete presented with a 2-year history of progressive left hip and groin pain. Extensive clinical examination and imaging confirmed the presence of cam-type femoroacetabular impingement, a labral tear and gluteal tendinopathy. Despite multiple intra and extra-articular pathologies, understanding the role of hip instability and implementing a rehabilitation exercise program focused on hip joint centration alleviated the patient's symptoms at rest and during activity.

SUMMARY

A robust history and physical exam of the hip is essential with the addition of imaging when testing criteria is positive. Clinicians should be aware of the role hip microinstability plays and its clinical implications when in the presence of other contributing factors such as generalized joint laxity, and/or intra-articular pathology.

Primary labral reconstruction in patients with femoroacetabular impingement, irreparable labral tears and severe acetabular chondral defects decreases the risk of conversion to total hip arthroplasty: a pair-matched study

In the presence of severe acetabular cartilage defects, the benefits of labral reconstruction (RECON) versus labral resection (RESEC) have not been determined. Prospectively collected data between October 2008 and December 2016 were retrospectively reviewed. Inclusion criteria were hip arthroscopy, acetabular Outerbridge grade III/IV, irreparable labral tears that underwent RECON or RESEC, and minimum 2-year postoperative measures for the modified Harris Hip Score, Non-Arthritic Hip Score, Hip Outcome Score-Sports Specific Subscale, International Hip Outcome Tool, Patient Satisfaction and Visual Analogue Scale for pain. Exclusion criteria included Tönnis grade >1, previous hip conditions or previous ipsilateral hip surgeries. A 1:1 matched-pair analysis was performed based on age ±5 years, sex, body mass index ±5 kg/m², Tönnis grade, acetabular microfracture, femoral Outerbridge grade (0 or I compared with II, III or IV). Relative risk (RR) and conversion rate to total hip arthroplasty (THA) were calculated. A total of 38 RECON hips were successfully matched. Both groups demonstrated significant improvements in patient-reported outcomes (PROs). THA conversion was 5.3% and 21.1% for the RECON and RESEC groups, respectively (P = 0.04). RECON was four times less likely to require THA conversion than the RESEC group (RR=4.0; 95% CI 0.91-17.63). In the setting of primary arthroscopic management of femoroacetabular impingement, irreparable labral tears and acetabular chondral lesions of Outerbridge III/IV, patients that underwent RECON and RESEC experienced significant improvement in PROs at minimum 2-year follow-up, and these functional scores were comparable when groups were matched. However, RR and rate to THA conversion were significantly higher in the RESEC group.

LENGTH CHANGE OF THE ILIOFEMORAL LIGAMENT DURING TESTS FOR ANTERIOR MICROINSTABILITY OF THE HIP JOINT: A CADAVERIC VALIDITY STUDY

PURPOSE/BACKGROUND

There is little information to support the use of clinical tests to assess for microinstability of the hip joint. The purpose of this study was to use a string model to describe and compare length changes of the iliofemoral ligament in the test positions commonly used to assess hip ligament laxity.

METHODS

Twelve hip joints from nine cadavers (4 male; 5 female) with lifespans of 57-84 years of age were studied. A string model representing the medial and lateral arms of the iliofemoral ligament was secured to the proximal and distal attachment points. The amount of length change of the string model was compared in four test positions: 1) external rotation, 2) hyperextension-external rotation 3) abduction-extension-external rotation, and 4) adduction--extension-external rotation.

RESULTS

For the medial arm, the greatest change occurred in the adduction-extension-external rotation position (12.7mm). This was significantly greater than the external rotation (5.1mm; p=0.002) and abduction-extension-external rotation position (1.9mm; p<0.001). The lateral arm also had the greatest excursion in the adduction-extension-external rotation position (16.6mm). This length change was significantly greater than the external rotation position (8.6mm; p=0.002), the hyperextension-external rotation (11.1mm; p=0.047), and the abduction-extension-external rotation position (5.6mm; p<0.001).

CONCLUSIONS

Tests used for hip instability cause various levels of tension through the iliofemoral ligament. The combination of hip extension and external rotation increased the length change of string model and was maximized with hip adduction. The least amount of change occurred with the addition of hip abduction to extension and external rotation.

CLINICAL RELEVANCE

Clinicians may use the information to help interpret tests for instability of the hip and may consider the combined position of hip extension, external rotation, and adduction to elucidate involvement of the iliofemoral femoral ligament.

LEVEL OF EVIDENCE

2b; Exploratory cohort study with good reference standards.

Can Dynamic Ultrasonography of the Hip Reliably Assess Anterior Femoral Head Translation?

BACKGROUND

Hip microinstability has gained attention recently as a potential cause of hip pain. Currently there is a lack of evidence-based objective diagnostic criteria surrounding this diagnosis. Previous studies have shown translation of the femoral head during extreme hip positions. However, reliable assessment of femoral head translation is lacking.

QUESTIONS/PURPOSES

(1) How precise is musculoskeletal ultrasound for measuring anterior femoral head translation during the hip anterior apprehension test? (2) What is the intra- and interrater reliability of dynamic ultrasonography in assessing anterior femoral head translation?

METHODS

We recruited 10 study participants (20 hips) between the ages of 22 and 50 years with no history of hip pain or functional limitations. Test-retest methodology was used. Seven females and three males were enrolled. The mean age of study participants was 27 years (SD 8.7 years); mean body mass index was 22.6 kg/m (SD 2.2 kg/m). All study participants underwent dynamic hip ultrasonography by three different physicians 1 week apart. Each hip was visualized in two neutral positions (neutral and neutral with the contralateral hip flexed [NF]) and two dynamic positions, which sought to replicate the apprehension test, although notably study participants had no known hip pathology and therefore no apprehension. The first maintained the hip in extension and external rotation off to the side of the examination table (EER1), and the second held the hip off of the bottom of the examination table (EER2). One hundred twenty ultrasound scans (480 images) were performed. Mean and SD were calculated using absolute values of the difference in ultrasound measurements (mm) between positions NF and EER1 and NF and EER2 calculated for each physician as well as an average of all three physicians. Intraclass correlation coefficient (ICC) analysis was used to examine intra- and interrater reliability.

RESULTS

The mean absolute difference for NF and EER1 was 0.84 mm (SD 0.93 mm) and for NF and EER2 0.62 mm (SD 0.40 mm) on Study Day 1. Similarly, on Study Day 2, the mean absolute difference for NF and EER1 position was 0.90 mm (SD 0.74 mm) and for NF and EER2 1.03 mm (SD 1.18 mm). Cumulative values of ICC analysis indicated excellent intrarater reliability in all four positions: neutral 0.794 (95% confidence interval [CI], 0.494-0.918), NF 0.927 (95% CI, 0.814-0.971), EER1 0.929 (95% CI, 0.825-0.972), and EER2 0.945 (95% CI, 0.864-0.978). Similarly, interrater ICC analysis cumulative values were excellent for NF, EER1, and EER2 and fair to good for the neutral position: neutral 0.725 (95% CI, 0.526-0.846), NF 0.846 (95% CI, 0.741-0.913), EER1 0.812 (95% CI, 0.674-0.895), and EER2 0.794 (95% CI, 0.652-0.884).

CONCLUSIONS

This study offers the first ultrasound protocol of which we are aware for measuring anterior femoral head translation. Hip dynamic ultrasound may assist in providing precise objective clinical-based diagnostic evidence when evaluating complex hip pain and suspected microinstability. Musculoskeletal ultrasound is a reliable office-based method of measuring anterior femoral head translation that can be utilized by physicians with varying experience levels. Future studies are needed to investigate ultrasound anterior femoral head translation taking into account sex, prior hip surgery, hip osseous morphology, and ligamentous laxity.

LEVEL OF EVIDENCE

Level III, diagnostic study.

Cam FAI and Smaller Neck Angles Increase Subchondral Bone Stresses During Squatting: A Finite Element Analysis

BACKGROUND

Individuals with a cam deformity and a decreased (varus) femoral neck-shaft angle may be predisposed to symptomatic femoroacetabular impingement (FAI). However, it is unclear what combined effects the cam deformity and neck angle have on acetabular cartilage and subchondral bone stresses during an impinging squat motion. We therefore used finite element analysis to examine the combined effects of cam morphology and femoral neck-shaft angle on acetabular cartilage and subchondral bone stresses during squatting, examining the differences in stress characteristics between symptomatic and asymptomatic individuals with cam deformities and individuals without cam deformities and no hip pain.

QUESTIONS/PURPOSES

Using finite element analysis in this population, we asked: (1) What are the differences in acetabular cartilage stresses? (2) What are the differences in subchondral bone stresses? (3) What are the effects of high and low femoral neck-shaft angles on these stresses?

METHODS

Six male participants were included to represent three groups (symptomatic cam, asymptomatic cam, control without cam deformity) with two participants per group, one with the highest femoral neck-shaft angle and one with the lowest (that is, most valgus and most varus neck angles, respectively). Each participant's finite element hip models were reconstructed from imaging data and assigned subject-specific bone material properties. Hip contact forces during squatting were determined and applied to the finite element models to examine maximum shear stresses in the acetabular cartilage and subchondral bone.

RESULTS

Both groups with cam deformities experienced higher subchondral bone stresses than cartilage stresses. Both groups with cam deformities also had higher subchondral bone stresses (symptomatic with high and low femoral neck-shaft angle = 14.1 and 15.8 MPa, respectively; asymptomatic with high and low femoral neck-shaft angle = 10.9 and 13.0 MPa, respectively) compared with the control subjects (high and low femoral neck-shaft angle = 6.4 and 6.5 MPa, respectively). The symptomatic and asymptomatic participants with low femoral neck-shaft angles had the highest cartilage and subchondral bone stresses in their respective subgroups. The asymptomatic participant with low femoral neck-shaft angle (123°) demonstrated anterolateral subchondral bone stresses (13.0 MPa), similar to the symptomatic group. The control group also showed no differences between cartilage and subchondral bone stresses.

CONCLUSIONS

The resultant subchondral bone stresses modeled here coincide with findings that acetabular subchondral bone is denser in hips with cam lesions. Future laboratory studies will expand the parametric finite element analyses, varying these anatomic and subchondral bone stiffness parameters to better understand the contributions to the pathomechanism of FAI.

CLINICAL RELEVANCE

Individuals with a cam deformity and more varus neck orientation may experience elevated subchondral bone stresses, which may increase the risks of early clinical signs and degenerative processes associated with FAI, whereas individuals with cam morphology and normal-to-higher femoral neck-shaft angles may be at lesser risk of disease progression that would potentially require surgical intervention.

Three-dimensional architecture of the ligamentum teres in the human hip joint

Background

We aimed to investigate the three-dimensional structure of the collagenous fibers of the ligamentum teres (LT) of the human hip and clarify the LT micro-anatomy at the attachment of the femoral head.

Methods

Femoral heads and LT were collected during hip arthroplasty. Specimens were cut into 5-10-mm squares, prepared, developed, and observed under a light microscope. Next, specimens were prepared and examined under a scanning electron microscope (SEM).

Results

Under optical microscope, LT adhered to the artificial cartilage at the attachment of the femoral head. Under SEM, LT comprised parallelly arranged collagenous fibers and the fine collagenous fibrils were twisted. While the central collagenous fibers of the LT at the attachment of the femoral head penetrated the articular cartilage tissue and reached the ring-shaped bone, fibers at the margin traversed and adhered to the cartilage surface.

Conclusion

Articular cartilage and subchondral bone are present at the LT attachment to the femoral head. Although collagenous fibers of the LT show parallel arrangement at the main trunk, they are dispersed at the cartilage surface and not all reach the thin subchondral bone of the femoral head. This could possibly weaken ligament strength at the attachment of the femoral head.

Level of evidence

IV.

Normal microscopic architecture of acetabular labrum of hip joint: a qualitative original study with clinical aspects

Background

Normal histologic architecture of acetabular labrum, regarding presence of Free Nerve Endings (FNEs) and Nerve End Organs (NEOs) has been four times described. Nevertheless, elderly cadaveric specimens and individuals were recruited, leading to considerably high unreliability probability due to microscopic degenerative alterations. Aim of this paper is to analyze distribution pattern of FNEs and NEOs in acetabular labra of healthy middle-aged individuals, configuring thus more reliably acetabular labrum microscopic profile.

Materials and methods

Six patients with middle age 52 ± 2.5 years were enrolled in this study. Injury of acetabular labrum and normal hip radiograph were present in all cases. Patients were all subjected to successful hip hemi-arthroplasty and derived acetabular labra were subsequently histologically processed and observed under a compound microscope.

Results

FNEs and NEOs were detected in all specimens. All types of NEOs were identified, including Paccini, Golgi-Mazzoni, Ruffini and Krause corpuscles. FNEs and NEOs were both in ventral part and in chondral side of labrum predominantly detected.

Conclusion

FNEs and NEOs presence was greater in ventral side of labrum, being thus in partial agreement with previous studies results. Further study is required, in order to elucidate the exact acetabular labrum normal microscopic anatomy.

Level of evidence

IV.