Translational relevance of the goat as a preclinical model of the human labrum and chondrolabral junction-histological study

Preoperative Paralabral Cysts Predict More Significant Chondral Damage but Not 2-Year Functional Outcomes Following Arthroscopic Labral Repair

PURPOSE

To investigate whether paralabral cysts identified incidentally on preoperative magnetic resonance imaging/arthrography predict 2-year functional outcomes after arthroscopic acetabular labral repair.

METHODS

Prospectively collected data for patients undergoing primary hip arthroscopy by a single surgeon from 2014 to 2020 were retrospectively reviewed. Included patients were ≥18 years and completed baseline patient-reported outcome measures (PROMs) with additional follow-up at 3, 6, 12, and 24 months. Exclusion criteria were labral debridement, hip dysplasia, advanced hip osteoarthritis (Tönnis > 1), or previous ipsilateral hip surgery. Patients were stratified based on the presence of paralabral cysts identified on magnetic resonance imaging/arthrography. Primary outcomes were International Hip Outcome Tool and modified Harris Hip Score. Secondary outcomes included other PROMs and the visual analog pain scale. Outcomes were compared between cohorts using linear mixed-effects models and Fisher's exact tests. Sensitivity analyses accounted for preoperative PROMs, nonlinear improvement trajectories, and relevant baseline characteristics.

RESULTS

Of the 182 included hips (47.8% female; mean ± standard deviation age, 36.9 ± 11.4), 30 (16.4%) had paralabral cysts. During the 2-year study period, there were no significant differences between patients with and without paralabral cysts in terms of International Hip Outcome Tool scores (weighted difference = 1.60; 95% confidence interval [CI], -5.09, 8.28; P = .64), modified Harris Hip Scores (weighted difference = 0.56; 95% CI, -4.16, 5.28; P = .82), or any secondary outcomes (except for HOS-Sports Subscale at 3 months [mean difference = -11.85; 95% CI, -22.85, -0.84; P = .035]). Furthermore, there were no significant differences in clinically meaningful outcomes (P > .05 for all), revision rates (P > .99), or conversion to total hip arthroplasty between cohorts (P > .99). These results held across all sensitivity analyses.

CONCLUSIONS

Although preoperative paralabral cysts were associated with worse cam impingement and more severe chondral damage observed intraoperatively, they did not predict 2-year functional outcomes or clinically meaningful improvements, suggesting that incidentally discovered paralabral cysts are not a contraindication for arthroscopic labral repair.

LEVEL OF EVIDENCE

Level III, retrospective cohort study.

Association Between Chondrolabral Junction Breakdown and Conversion to Total Hip Arthroplasty After Hip Arthroscopy for Symptomatic Labral Tears: Minimum 8-Year Follow-up

BACKGROUND

Arthroscopic treatment of femoroacetabular impingement (FAI) and symptomatic labral tears confers short- to midterm benefits, yet further long-term evidence is needed. Moreover, despite the physiological and biomechanical significance of the chondrolabral junction (CLJ), the clinical implications of damage to this transition zone remain understudied.

PURPOSE

To (1) report minimum 8-year survivorship and patient-reported outcome measures after hip arthroscopy for FAI and (2) characterize associations between outcomes and patient characteristics (age, body mass index, sex), pathological parameters (Tönnis angle, alpha angle, type of FAI, CLJ breakdown), and procedures performed (labral management, FAI treatment, microfracture).

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

This retrospective cohort study included patients who underwent primary hip arthroscopy for symptomatic labral tears secondary to FAI by a single surgeon between 2002 and 2013. All patients were ≥18 years of age with minimum 8-year follow-up and available preoperative radiographs. The primary outcome was conversion to total hip arthroplasty (THA), and secondary outcomes included revision arthroscopy, patient-reported outcome measures, and patient satisfaction. CLJ breakdown was assessed using the Beck classification. Kaplan-Meier estimates and weighted Cox regression were used to estimate 10-year survivorship (no conversion to THA) and identify risk factors associated with THA conversion.

RESULTS

In this study of 174 hips (50.6% female; mean age, 37.8 ± 11.2 years) with mean follow-up of 11.1 ± 2.5 years, the 10-year survivorship rate was 81.6% (95% CI, 75.9%-87.7%). Conversion to THA occurred at a mean 4.7 ± 3.8 years postoperatively. Unadjusted analyses revealed several variables significantly associated with THA conversion, including older age; higher body mass index; higher Tönnis grade; labral debridement; and advanced breakdown of the CLJ, labrum, or articular cartilage. Survivorship at 10 years was inferior in patients exhibiting severe (43.6%; 95% CI, 31.9%-59.7%) versus mild (97.9%; 95% CI, 95.1%-100%) breakdown of the CLJ (P < .001). Multivariable analysis identified worsening CLJ breakdown (weighted hazard ratio per 1-unit increase, 6.41; 95% CI, 3.11-13.24), older age (1.09; 95% CI, 1.04-1.14), and higher Tönnis grade (4.59; 95% CI, 2.13-9.90) as independent negative prognosticators (P < .001 for all).

CONCLUSION

Although most patients achieved favorable minimum 8-year outcomes, several pre- and intraoperative factors were associated with THA conversion; of these, worse CLJ breakdown, higher Tönnis grade, and older age were the strongest predictors.

Minimum 2-Year Functional Outcomes of Patients Undergoing Capsular Autograft Hip Labral Reconstruction

BACKGROUND

There is a paucity of literature on arthroscopic capsular autograft labral reconstruction.

PURPOSE

To report midterm functional outcomes for patients undergoing acetabular labral repair with capsular autograft labral reconstruction.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

This is a retrospective case series of prospectively collected data on patients who underwent arthroscopic acetabular labral repair by the senior surgeon between March 2013 and August 2018. The inclusion criteria for this study were adult patients aged 18 years or older who underwent primary hip arthroscopy for arthroscopic capsular autograft labral reconstruction. Exclusion criteria were <2 years of postoperative follow-up, elective disenrollment from study before 2-year follow-up, or repeat ipsilateral hip surgery before 2-year follow-up. Intraoperatively, patients underwent capsular autograft hip labral reconstruction if they were found to have a labrum with hypoplastic tissue (width <5 mm), complex tearing, or frank degeneration of native tissue. Clinical outcome data consisted of patient-reported outcome measures.

RESULTS

A total of 97 hips (94 patients) met the inclusion criteria with a mean final follow-up of 28.2 months (95% CI, 26.0-30.4). Patients had a mean age of 39.0 years (95% CI, 36.8-41.2) with a mean body mass index of 25.8 (95% CI, 24.9-26.7). When compared with baseline (40.4 [95% CI, 36.7-44.2]), the mean international Hip-Outcome Tool-33 (iHOT-33) scores were significantly greater at 3-month (60.9 [95% CI, 56.8-64.9]; P < .001), 6-month (68.8 [95% CI, 64.7-72.9]; P < .001), 12-month (73.2 [95% CI, 68.9-77.5]; P < .001), and final (76.6 [95% CI, 72.4-80.8]; P < .001) follow-up. At 2-year follow-up, 76.3%, 65.5%, and 60.8% of patients' iHOT-33 scores exceeded clinically meaningful outcome thresholds for minimally clinically important difference (MCID), patient-acceptable symptomatic state, and substantial clinical benefit, respectively.

CONCLUSIONS

In this study of 97 hips undergoing arthroscopic labral repair with capsular autograft labral reconstruction, we found favorable outcomes that exceeded the MCID thresholds in the majority of patients at a mean 28.2 months' follow-up. Future studies should compare outcomes between this technique and other methods of autograft and allograft reconstruction to determine differences in patient-reported outcomes, donor-site morbidity, and complications.

Platelet-Derived Growth Factor Stimulated Migration of Bone Marrow Mesenchymal Stem Cells into an Injectable Gelatin-Hydroxyphenyl Propionic Acid Matrix

Bone marrow mesenchymal stem cells (bMSCs) are responsible in the repair of injured tissue through differentiation into multiple cell types and secretion of paracrine factors, and thus have a broad application profile in tissue engineering/regenerative medicine, especially for the musculoskeletal system. The lesion due to injury or disease may be a closed irregular-shaped cavity deep within tissue necessitating an injectable biomaterial permissive of host (endogenous) cell migration, proliferation and differentiation. Gelatin-hydroxyphenyl propionic acid (Gtn-HPA) is a natural biopolymer hydrogel which is covalently cross-linked by horseradish peroxidase (HRP) and hydrogen peroxide (H₂O₂) in situ and can be delivered to the lesion by needle injection. Growth factors and cytokines can be directly incorporated into the gel or into nano- and micro-particles, which can be employed for sustained release of biomolecules while maintaining their bioactivity. In this study, we selected polyelectrolyte complex nanoparticles (PCNs) prepared with dextran sulfate and chitosan as the carrier for platelet-derived growth factor (PDGF)-BB and stromal cell-derived factor (SDF)-1α, which have been tested effectively in recruiting stem cells. Our in vitro results showed a high degree of viability of bMSCs through the process of Gtn-HPA covalent cross-linking gelation. The Gtn-HPA matrix was highly permissive of bMSC migration, proliferation, and differentiation. PDGF-BB (20 ng/mL) directly incorporated into the gel and, alternatively, released from PCNs stimulated bMSC migration and proliferation. There were only small differences in the results for the direct incorporation of PDGF into the gel compared with its release from PCNs, and for increased doses of the growth factor (200 ng/mL and 2 µg/mL). In contrast, SDF-1α elicited an increase in migration and proliferation only when released from PCNs; its effect on migration was notably less than PDGF-BB. The in vitro results demonstrate that PDGF-BB substantially increases migration of bMSCs into Gtn-HPA and their proliferation in the gel, and that these benefits can be derived from incorporation of a relatively low dose of the growth factor directly into the gel. These findings commend the use of Gtn-HPA/PDGF-BB as an injectable therapeutic agent to treat defects in musculoskeletal tissues.