A multibody model of the knee was developed and the predicted ligament forces and kinematics during passive flexion corroborated subject-specific measurements obtained from a human cadaveric knee that was tested using a robotic manipulator. The model incorporated a novel strategy to estimate the slack length of ligament fibers based on experimentally measured ligament forces at full extension and included multifiber representations for the cruciates. The model captured experimentally measured ligament forces (≤ 5.7 N root mean square (RMS) difference), coupled internal rotation (≤ 1.6 deg RMS difference), and coupled anterior translation (≤ 0.4 mm RMS difference) through 130 deg of passive flexion. This integrated framework of model and experiment improves our understanding of how passive structures, such as ligaments and articular geometries, interact to generate knee kinematics and ligament forces.
It may be advantageous to create a "higher" femoral tunnel during ACL reconstruction at the lateral intercondylar ridge.
Background:Symptomatic articular cartilage lesions of the knee are common and are being treated surgically with increasing frequency. While many studies have reported outcomes following a variety of cartilage restoration procedures, few have investigated outcomes of revision surgery after a failed attempt at cartilage repair or reconstruction.Purpose:To investigate outcomes of revision cartilage restoration procedures for symptomatic articular cartilage lesions of the knee following a previously failed cartilage reconstructive procedure.Study Design:Systematic review; Level of evidence, 4.Methods:A literature search was performed by use of the PubMed, EMBASE, and MEDLINE/Ovid databases for relevant articles published between 1975 and 2017 that evaluated patients undergoing revision cartilage restoration procedure(s) and reported outcomes using validated outcome measures. For studies meeting inclusion criteria, relevant information was extracted.Results:Ten studies met the inclusion criteria. Lesions most commonly occurred in the medial femoral condyle (MFC) (52.8%), with marrow stimulation techniques (MST) the index procedure most frequently performed (70.7%). Three studies demonstrated inferior outcomes of autologous chondrocyte implantation (ACI) following a previous failed cartilage procedure compared with primary ACI. One study comparing osteochondral allograft (OCA) transplant following failed microfracture (MFX) with primary OCA transplant demonstrated similar clinical outcomes and graft survival at midterm follow-up. No studies reported outcomes following osteochondral autograft transfer (OAT) or newer techniques.Conclusion:This systematic review of the literature reporting outcomes following revision articular cartilage restoration procedures (most commonly involving the MFC) demonstrated a high proportion of patients who underwent prior MST. Evidence is sufficient to suggest that caution should be taken in performing ACI in the setting of prior MST, likely secondary to subchondral bone compromise. OCA appears to be a good revision treatment option even if the subchondral bone has been violated from prior surgery or fracture.
Background: Preoperative emotional distress has been shown to negatively influence joint arthroplasty and spine surgery, but limited data exist for foot and ankle outcomes. Emotional distress can be captured through modern tools like the Patient-Reported Outcomes Instrument Measurement System (PROMIS) anxiety domain. We hypothesized that patients with greater preoperative PROMIS anxiety scores would report greater pain and less function after foot and ankle surgery than patients with lower preoperative anxiety levels. Methods: Elective foot and ankle surgeries from May 2016 to December 2017 were retrospectively identified. PROMIS anxiety, pain interference (PI), and physical function (PF) scores were collected before and after surgery. Patients were grouped based on preoperative PROMIS scores greater or less than 59.4. A cutoff of PROMIS anxiety above 59.4 was selected as the threshold that corresponds to traditional measures of anxiety. Results: Compared to patients with less preoperative anxiety (average: 47.2, n=146), patients with higher preoperative anxiety (average: 63.9, n=59) had greater preoperative pain (PROMIS PI: 63.5 vs 59.1, P < .001) and lower physical function (PROMIS PF: 37.9 vs 42.0, P = .001). Postoperatively, patients with higher preoperative anxiety had more residual pain and greater functional disability as compared to patients with less preoperative emotional distress (PROMIS PI: 58.6 vs 52.9, P < .001; PROMIS PF: 39.8 vs 44.4, P < .001; respectively). Conclusion: Our evidence showed that preoperative emotional anxiety predicted worse pain and function at early operative follow-up. Measures of preoperative anxiety could be useful in identifying patients at risk for poorer operative outcomes, but continued study is necessary. Level of Evidence: Level III, retrospective comparative study.
Both the sMCL and POL work together with the ACL to resist combined moments, which form key components of the pivot-shift examination.
Context: Patients with anterior cruciate ligament (ACL) tears are likely to have deficient dynamic postural stability compared with healthy sex- and age-matched controls. Objectives: To test the hypothesis that patients undergoing ACL reconstruction have decreased dynamic postural stability compared with matched healthy controls. Design: Prospective case-control study. Setting: Orthopedic sports medicine and physical therapy clinics. Patients or Other Participants: Patients aged 20 years and younger with an ACL tear scheduled for reconstruction were enrolled prospectively. Controls were recruited from local high schools and colleges via flyers. Interventions: Patients underwent double-stance dynamic postural stability testing prior to surgery, recording time to failure and dynamic motion analysis (DMA) scores. Patients were then matched with healthy controls. Main Outcome Measures: Demographics, time to failure, and DMA scores were compared between groups. Results: A total of 19 females and 12 males with ACL tears were matched with controls. Individuals with ACL tears were more active (Marx activity score: 15.7 [1.0] vs 10.8 [4.9], P < .001); had shorter times until test failure (84.4 [15.8] vs 99.5 [14.5] s, P < .001); and had higher (worse) DMA scores (627 [147] vs 481 [132], P < .001), indicating less dynamic postural stability. Six patients with ACL deficiency (1 male and 5 females) demonstrated lower (better) DMA scores than their controls, and another 7 (4 males and 3 females) were within 20% of controls. Conclusions: Patients undergoing ACL reconstruction had worse global dynamic postural stability compared with well-matched controls. This may represent the effect of the ACL injury or preexisting deficits that contributed to the injury itself. These differences should be studied further to evaluate their relevance to ACL injury risk, rehabilitation, and return to play.
Background: The anterior cruciate ligament (ACL) is crucial for knee proprioception and postural stability. While ACL reconstruction (ACLR) and rehabilitation improve postural stability, the timing in improvement of dynamic postural stability after ACLR remains relatively unknown. Purpose: To evaluate changes in dynamic postural stability after ACLR out to 24 months postoperatively. Study Design: Case series; Level of evidence, 4. Methods: Patients undergoing ACLR were prospectively enrolled, and dynamic postural stability was assessed within 2 days before surgery, at 3-month intervals postoperatively to 18 months, then at 24 months. Measurements were made on a multidirectional platform tracking the patient’s center of mass based on pelvic motion. The amount of time the patient was able to stay on the platform was recorded, and a dynamic motion analysis score, reflecting the patient’s ability to maintain one’s center of mass, was generated overall and in 6 independent planes of motion. Results: A total of 44 patients with a mean age of 19.7 ± 6.2 years completed the study protocol. Overall mean dynamic postural stability improved significantly at 3, 6, 9, and 12 months after surgery, with continued improvement out to 24 months. Notable improvements occurred in medial/lateral and anterior/posterior stability from baseline to 6 months postoperatively, while internal/external rotation and flexion/extension stability declined initially after surgery from baseline to 3 months postoperatively before stabilizing to the end of the study period. Conclusion: Overall dynamic postural stability significantly improved up to 12 months after ACLR. Improvement in postural stability occurred primarily in the medial/lateral and anterior/posterior planes of motion, with initial decreases in the flexion/extension and internal/external rotational planes of motion.
Background: A modified version of the International Knee Documentation Committee (IKDC), the Pedi-IKDC, is a validated patient-reported outcome measure in pediatric patients with knee pain. However, this questionnaire is lengthy and can fatigue patients, leading to inconsistent outcome collection. Thus, we sought to compare more easily attainable Patient-Reported Outcomes Measurement Information System (PROMIS) computer adaptive testing patient reported outcomes to the gold standard Pedi-IKDC. Methods: We prospectively collected PROMIS scores and Pedi-IKDC scores in 100 new, consecutive patients presenting with knee pain to a pediatric sports medicine practice. Patients were excluded if they provided an incomplete Pedi-IKDC, had prior ipsilateral lower extremity surgery, or significant associated medical comorbidities. PROMIS domains including Mobility, Pain Interference, and Upper Extremity (control) were compared with the Pedi-IKDC with Pearson correlations. The number of questions in each metric was analyzed. Floor and ceiling effects of each test were also assessed. Results: The average age of the study cohort was 14 years (range, 7 to 18 y) with 53% female and 47% male. 70% of patients completed the Pedi-IKDC questionnaire, compared with 100% with PROMIS tests. The average Pedi-IKDC score was 48.8±22.3 (range, 5.4 to 100). Mean scores for Mobility, Pain Interference, and Upper Extremity domains were 38.4±10.1, 53.5±10.3, and 49.7±8.7, respectively. All tests demonstrated similar and acceptable floor and ceiling effects (<15%). The length of the Pedi-IKDC (22 questions) was roughly double that of combined PROMIS Pain Interference and Mobility tests (11.9±2.3 questions). Pedi-IKDC scores correlated with tested PROMIS measures (Mobility/Pain Interference, r=0.42/−0.49). When 7 highly functional patients with significant pain symptoms were removed for a secondary analysis, Mobility and Pain correlations improved to 0.69 and −0.67, respectively. Conclusions: PROMIS Mobility and Pain scores demonstrate moderate correlations with the Pedi-IKDC, highlighting these tests are not capturing the same patient experiences. These correlations are weakened by a small group of painful yet highly functioning patients. The Pedi-IKDC was significantly longer and had a much lower completion rate than PROMIS tests, highlighting a need for a validated computer adaptive testing in evaluating pediatric patients with knee pain. Levels of Evidence: Level II.
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