Elizabeth R. Sibilsky Enselman

Intraoperative Fluoroscopic Imaging to Treat Cam Deformities Correlation With 3-Dimensional Computed Tomography

Background: In the diagnosis and surgical treatment of cam-type femoroacetabular impingement (FAI), 3-dimensional (3D) imaging is the gold standard for detecting femoral head-neck junction malformations preoperatively. Intraoperative fluoroscopy is used by many surgeons to evaluate and verify adequate correction of the deformity. Purpose: (1) To compare radial reformatted computed tomography (CT) scans with 6 defined intraoperative fluoroscopic views before surgical correction to determine whether fluoroscopy could adequately depict cam deformity, and (2) to define the influence of femoral version on the clock-face location of the maximum cam deformity on these views. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: A consecutive series of 50 hips (48 patients) that underwent arthroscopic treatment for symptomatic FAI by a single surgeon were analyzed. Each patient underwent a CT scan and 6 consistent intraoperative fluoroscopy views: 3 views in hip extension and 3 views in hip flexion of 50°. The alpha angles of each of the fluoroscopic images were compared with the radial reformatted CT using a 3D software program. Femoral version was also defined on CT studies. Statistical analysis was performed using the Student t test, with P < .05 defined as significant. Results: Fifty-two percent of patients were male, average age 28 years (range, 15-56 years). The maximum mean alpha angle on fluoroscopy was 65° (range, 37°-93°) and was located on the anteroposterior (AP) 30° external rotation (ER) fluoroscopy view. In comparison, the mean CT-derived maximum alpha angle was 67° and was located at 1:15 (P = .57). The mean clock-face positions of each of the fluoroscopy views (standardized to the right hip) were AP 30° internal rotation, 11:45; AP 0° (neutral) rotation, 12:30; AP 30° ER, 1:00; flexion/0° (neutral) rotation, 1:45; flexion/40° ER, 2:15; and flexion/60° ER, 2:45. Increased femoral anteversion (>20°) was associated with a significant change in the location of the maximum alpha angle (1:45 vs 1:15; P = .002). Conclusion: The described 6 fluoroscopic views are very helpful in localization and visualization of the typical cam deformity from 11:45 to 2:45 and can be used to reliably confirm a complete intraoperative resection of cam-type deformity in most patients. These views correlate with preoperative 3D imaging and may be of even greater importance in the absence of preoperative 3D imaging.

Cartilage Restoration of the Knee A Systematic Review and Meta-Analysis of Level 1 Studies

Background: Focal cartilage defects of the knee are a substantial cause of pain and disability in active patients. There has been an emergence of randomized controlled trials evaluating surgical techniques to manage such injuries, including marrow stimulation (MS), autologous chondrocyte implantation (ACI), and osteochondral autograft transfer (OAT). Purpose: A meta-analysis was conducted to determine if any single technique provides superior clinical results at intermediate follow-up. Study Design: Systematic review and meta-analysis of randomized controlled trials. Methods: The MEDLINE, EMBASE, and Cochrane Library databases were systematically searched and supplemented with manual searches of PubMed and reference lists. Eligible studies consisted exclusively of randomized controlled trials comparing MS, ACI, or OAT techniques in patients with focal cartilage defects of the knee. The primary outcome of interest was function (Lysholm score, International Knee Documentation Committee score, Knee Osteoarthritis Outcome Score) and pain at 24 months postoperatively. A meta-analysis using standardized mean differences was performed to provide a pooled estimate of effect comparing treatments. Results: A total of 12 eligible randomized trials with a cumulative sample size of 765 patients (62% males) and a mean (±SD) lesion size of 3.9 ± 1.3 cm2 were included in this review. There were 5 trials comparing ACI with MS, 3 comparing ACI with OAT, and 3 evaluating different generations of ACI. In a pooled analysis comparing ACI with MS, there was no difference in outcomes at 24-month follow-up for function (standardized mean difference, 0.47 [95% CI, –0.19 to 1.13]; P = .16) or pain (standardized mean difference, –0.13 [95% CI, –0.39 to 0.13]; P = .33). The comparisons of ACI to OAT or between different generations of ACI were not amenable to pooled analysis. Overall, 5 of the 6 trials concluded that there was no significant difference in functional outcomes between ACI and OAT or between generations of ACI. Conclusion: There is no significant difference between MS, ACI, and OAT in improving function and pain at intermediate-term follow-up. Further randomized trials with long-term outcomes are warranted.

Elevation in Circulating Biomarkers of Cartilage Damage and Inflammation in Athletes With Femoroacetabular Impingement

Background: Femoroacetabular impingement (FAI) is one of the most common causes of early cartilage and labral damage in the nondysplastic hip. Biomarkers of cartilage degradation and inflammation are associated with osteoarthritis. It was not known whether patients with FAI have elevated levels of biomarkers of cartilage degradation and inflammation. Hypothesis: Compared with athletes without FAI, athletes with FAI would have elevated levels of the inflammatory C-reactive protein (CRP) and cartilage oligomeric matrix protein (COMP), a cartilage degradation marker. Study Design: Controlled laboratory study. Methods: Male athletes with radiographically confirmed FAI (n = 10) were compared with male athletes with radiographically normal hips with no evidence of FAI or hip dysplasia (n = 19). Plasma levels of COMP and CRP were measured, and subjects also completed the Short Form–12 (SF-12) and Hip Disability and Osteoarthritis Outcome Score (HOOS) surveys. Results: Compared with controls, athletes with FAI had a 24% increase in COMP levels and a 276% increase in CRP levels as well as a 22% decrease in SF-12 physical component scores and decreases in all of the HOOS subscale scores. Conclusion: Athletes with FAI demonstrate early biochemical signs of increased cartilage turnover and systemic inflammation. Clinical Relevance: Chondral injury secondary to the repetitive microtrauma of FAI might be reliably detected with biomarkers. In the future, these biomarkers might be used as screening tools to identify at-risk patients and assess the efficacy of therapeutic interventions such as hip preservation surgery in altering the natural history and progression to osteoarthritis.

Changes in Circulating Biomarkers of Muscle Atrophy, Inflammation, and Cartilage Turnover in Patients Undergoing Anterior Cruciate Ligament Reconstruction and Rehabilitation

Background: After anterior cruciate ligament (ACL) reconstruction, there is significant atrophy of the quadriceps muscles that can limit full recovery and place athletes at risk for recurrent injuries with return to play. The cause of this muscle atrophy is not fully understood. Hypothesis: Circulating levels of proatrophy, proinflammatory, and cartilage turnover cytokines and biomarkers would increase after ACL reconstruction. Study Design: Descriptive laboratory study. Methods: Patients (N = 18; mean age, 28 ± 2.4 years) underwent surgical reconstruction of the ACL after a noncontact athletic injury. Circulating levels of biomarkers were measured along with Short Form−12, International Knee Documentation Committee, and objective knee strength measures preoperatively and at 6 postoperative visits. Differences were tested using repeated-measures 1-way analysis of variance. Results: Myostatin, TGF-β, and C-reactive protein levels were significantly increased in the early postoperative period and returned to baseline. Cartilage oligomeric matrix protein levels decreased immediately after surgery and then returned to baseline. CCL2, CCL3, CCL4, CCL5, EGF, FGF-2, IGF-1, IL-10, IL-1α, IL-1β, IL-1ra, IL-6, myoglobin, and TNF-α were not different over the course of the study. Conclusion: An increase in potent atrophy-inducing cytokines and corresponding changes in knee strength and functional scores were observed after ACL reconstruction. Clinical Relevance: Although further studies are necessary, the therapeutic inhibition of myostatin may help prevent the muscle atrophy that occurs after ACL reconstruction and provide an accelerated return of patients to sport.

Reduced muscle fiber force production and disrupted myofibril architecture in patients with chronic rotator cuff tears

BACKGROUND A persistent atrophy of muscle fibers and an accumulation of fat, collectively referred to as fatty degeneration, commonly occur in patients with chronic rotator cuff tears. The etiology of fatty degeneration and function of the residual rotator cuff musculature have not been well characterized in humans. We hypothesized that muscles from patients with chronic rotator cuff tears have reduced muscle fiber force production, disordered myofibrils, and an accumulation of fat vacuoles. METHODS The contractility of muscle fibers from biopsy specimens of supraspinatus muscles of 13 patients with chronic full-thickness posterosuperior rotator cuff tears was measured and compared with data from healthy vastus lateralis muscle fibers. Correlations between muscle fiber contractility, American Shoulder and Elbow Surgeons (ASES) scores, and tear size were analyzed. Histology and electron microscopy were also performed. RESULTS Torn supraspinatus muscles had a 30% reduction in maximum isometric force production and a 29% reduction in normalized force compared with controls. Normalized supraspinatus fiber force positively correlated with ASES score and negatively correlated with tear size. Disordered sarcomeres were noted, along with an accumulation of lipid-laden macrophages in the extracellular matrix surrounding supraspinatus muscle fibers. CONCLUSIONS Patients with chronic supraspinatus tears have significant reductions in muscle fiber force production. Force production also correlates with ASES scores and tear size. The structural and functional muscle dysfunction of the residual muscle fibers is independent of the additional area taken up by fibrotic tissue. This work may help establish future therapies to restore muscle function after the repair of chronically torn rotator cuff muscles.

Tendon contraction after cyclic elongation is an age-dependent phenomenon: In vitro and in vivo comparisons

Background: Tendons are viscoelastic tissues that deform (elongate) in response to cyclic loading. However, the ability of a tendon to recover this elongation is unknown. Hypothesis: Tendon length significantly increases after in vivo or in vitro cyclic loading, and the ability to return to its original length through a cell-mediated contraction mechanism is an age-dependent phenomenon. Study Design: Controlled laboratory study. Methods: In vitro, rat tail tendon fascicles (RTTfs) from Sprague-Dawley rats of 3 age groups (1, 3, and 12 months) underwent 2% cyclic strain at 0.17 Hz for 2 hours, and the percentages of elongation were determined. After loading, the RTTfs were suspended for 3 days under tissue culture conditions and photographed daily to determine the amount of length contraction. In vivo, healthy male participants (n = 29; age, 19-49 years) had lateral, single-legged weightbearing radiographs taken of the knee at 60° of flexion immediately before, immediately after, and 24 hours after completing eccentric quadriceps loading exercises on the dominant leg to fatigue. Measurements of patellar tendon length were taken from the radiographs, and the percentages of tendon elongation and subsequent contraction were calculated. Results: In vitro, cyclic loading increased the length of all RTTfs, with specimens from younger (1 and 3 months) rats demonstrating significantly greater elongation than those from older (12 months) rats (P = .009). The RTTfs contracted to their original length significantly faster (P < .001) and in an age-dependent fashion, with younger animals contracting faster. In vivo, repetitive eccentric loading exercises significantly increased patellar tendon length (P < .001). Patellar tendon length decreased 24 hours after exercises (P < .001) but did not recover completely (P < .001). There was a weak but significant (R 2 = 0.203, P = .014) linear correlation between the amount of tendon contraction and age, with younger participants (<30 years) demonstrating significantly more contraction (P = .014) at 24 hours than older participants (>30 years). Conclusion: Cyclic tendon loading results in a significant increase in tendon elongation under both in vitro and in vivo conditions. Tendons in both conditions demonstrated an incomplete return to their original length after 24 hours, and the extent of this return was age dependent. Clinical Relevance: The age- and time-dependent contraction of tendons, elongated after repetitive loading, could result in transient alterations in the mechanobiological environment of tendon cells. This, in turn, could induce the onset of catabolic changes associated with the pathogenesis of tendinopathy. These results suggest the importance of allowing time for contraction between bouts of repetitive exercise and may explain why age is a predisposing factor in tendinopathy.

Anterior cruciate ligament tear induces a sustained loss of muscle fiber force production: Short Reports

Introduction: Patients with anterior cruciate ligament (ACL) tears have persistent quadriceps strength deficits that are thought to be due to altered neurophysiological function. Our goal was to determine the changes in muscle fiber contractility independent of the ability of motor neurons to activate fibers. Methods: We obtained quadriceps biopsies of patients undergoing ACL reconstruction, and additional biopsies 1, 2, and 6 months after surgery. Muscles fiber contractility was assessed in vitro, along with whole muscle strength testing. Results: Compared with controls, patients had a 30% reduction in normalized muscle fiber force at the time of surgery. One month later, the force deficit was 41%, and at 6 months the deficit was 23%. Whole muscle strength testing demonstrated similar trends. Discussion: While neurophysiological dysfunction contributes to whole muscle weakness, there is also a reduction in the force generating capacity of individual muscle cells independent of alpha motor neuron activation. Muscle Nerve 58: 145–148, 2018

Hip preservation: Current concepts and future frontiers

The rapid growth in hip preservation surgery has been paralleled by a commensurate increase in clinical questions and challenges. While our technical capabilities to achieve surgical correction of hip pathoanatomy have seen tremendous advances with arthroscopic techniques, the appropriate indications and impact of these procedures on the natural history of hip impingement and dysplasia have yet to be defined. Pushing the envelope to new frontiers with arthroscopic hip surgery must be balanced with responsible and evidence-based review of clinical outcomes. Furthermore, the power and utility of open corrective procedures, including surgical dislocation of the hip or osteotomies, is tremendous, and these interventions are often necessary to achieve a full correction of the anatomy and biomechanics of the joint. Arthroscopic and open approaches remain complementary and potentially synergistic, and the pathology should guide selection of the best approach to preserve the hip joint. “Minimally invasive” at the price of incomplete treatment is a failure for the surgeon and the patient, but “maximally invasive” and the associated challenging recovery may not be necessary for many previously inaccessible deformities. Translational research studies that examine the biochemical, biomechanical, and kinematic effects of our interventions provide the fundamental data necessary to further evolve our understanding and the indications for treatment in various patient populations. Computer-assisted dynamic analysis of 3-dimensional imaging is a new and powerful tool to help us understand and directly visualize intra-articular and extraarticular mechanical conflicts that may correlate with symptomatic presentations in active patients. In the current issue, we are proud to present a series of thoughtful and organized manuscripts that visit some of these topical issues in hip preservation surgery. Thought leaders in the field provide a balanced summary of the evidence in the literature to date, as well as their preferred approaches to managing active patients with symptomatic hip pain. We also present some discussion on new frontiers in arthroscopic hip surgery, including treatment of dysplasia as well as periarticular soft tissue pathology. We are very grateful to the authors for their contributions and to the SMAR readership for their interest in this exciting field.