Localized Anterior Arthrofibrosis After Soft-Tissue Quadriceps Tendon Anterior Cruciate Ligament Reconstruction Is More Common in Patients Who Are Female, Undergo Meniscal Repair, and Have Grafts of Larger Diameter.

PURPOSE: To determine factors associated with localized anterior arthrofibrosis (cyclops lesion), such as graft size, warranting early reoperation for lysis of adhesions after anterior cruciate ligament reconstruction (ACLR) with all-soft tissue quadriceps tendon (ASTQT) autograft. METHODS: All primary ASTQT autograft ACLRs within a single surgeon's prospectively collected registry with minimum 6-month follow-up were included. Patients who underwent multiligament knee reconstruction or cartilage restoration procedures were excluded. Localized anterior arthrofibrosis was defined as the requirement for a second procedure to achieve debridement and lysis of adhesions owing to the inability to regain terminal extension within 6 months of ACLR. The sex-specific incidence of arthrofibrosis was evaluated relative to age, weight, femoral and tibial tunnel sizes, meniscal repair, and meniscectomy by a binary logistic regression. RESULTS: This study included 721 patients (46% female patients). There were 52 cases of localized anterior arthrofibrosis (7.2%). Female patients had a greater incidence of arthrofibrosis than male patients. Male patients with a femoral tunnel diameter of 9.25 mm or greater had an increased incidence of arthrofibrosis compared with those with a diameter of less than 9.25 mm, whereas a similar cutoff was not found to be statistically significant for female patients. Concomitant meniscal repair was associated with an increased risk of arthrofibrosis. CONCLUSIONS: Female sex and concomitant meniscal repair were associated with an increased localized anterior arthrofibrosis incidence. Furthermore, ASTQT with a femoral tunnel diameter of 9.25 mm or greater in male patients was associated with an increased incidence of arthrofibrosis. LEVEL OF EVIDENCE: Level III, retrospective, comparative prognostic trial.

Detection of Meniscal Tear Effects on Tibial Vibration Using Passive Knee Sound Measurements.

OBJECTIVE: To evaluate whether non-invasive knee sound measurements can provide information related to the underlying structural changes in the knee following meniscal tear. These changes are explained using an equivalent vibrational model of the knee-tibia structure. METHODS: First, we formed an analytical model by modeling the tibia as a cantilever beam with the fixed end being the knee. The knee end was supported by three lumped components with features corresponding with tibial stiffnesses, and meniscal damping effect. Second, we recorded knee sounds from 46 healthy legs and 9 legs with acute meniscal tears (n = 34 subjects). We developed an acoustic event ("click") detection algorithm to find patterns in the recordings, and used the instrumental variable continuous-time transfer function estimation algorithm to model them. RESULTS: The knee sound measurements yielded consistently lower fundamental mode decay rate in legs with meniscal tears ( 16 ±13 s - 1) compared to healthy legs ( 182 ±128 s - 1), p < 0.05. When we performed an intra-subject analysis of the injured versus contralateral legs for the 9 subjects with meniscus tears, we observed significantly lower natural frequency and damping ratio (first mode results for healthy: [Formula: see text]injured: [Formula: see text]) for the first three vibration modes (p < 0.05). These results agreed with the theoretical expectations gleaned from the vibrational model. SIGNIFICANCE: This combined analytical and experimental method improves our understanding of how vibrations can describe the underlying structural changes in the knee following meniscal tear, and supports their use as a tool for future efforts in non-invasively diagnosing meniscal tear injuries.

Liposomal Bupivacaine for Pain Control After Anterior Cruciate Ligament Reconstruction: A Prospective, Double-Blinded, Randomized, Positive-Controlled Trial.

BACKGROUND: Local anesthetics are commonly administered into surgical sites as a part of multimodal pain control regimens. Liposomal bupivacaine is a novel formulation of bupivacaine designed for slow diffusion of a single dose of local anesthetic over a 72-hour period. While early results are promising in various settings, no studies have compared pain management regimens containing liposomal bupivacaine to traditional regimens in patients undergoing anterior cruciate ligament (ACL) reconstruction. PURPOSE: To evaluate liposomal bupivacaine in comparison with 0.25% bupivacaine hydrochloride (HCl) for pain control after ACL reconstruction. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: A total of 32 adult patients undergoing primary ACL reconstruction with a soft tissue quadriceps tendon autograft between July 2014 and March 2015 were enrolled. All patients received a femoral nerve block immediately before surgery. Patients then received either a 40-mL suspension of 20 mL Exparel (1 vial of bupivacaine liposome injectable suspension) and 20 mL 0.9% injectable saline or 20 mL 0.5% bupivacaine HCl and 20 mL 0.9% injectable saline, which was administered into the graft harvest site and portal sites during surgery. Patients were given either a postoperative smartphone application or paper-based journal to record data for 1 week after ACL reconstruction. RESULTS: Of the 32 patients recruited, 29 patients were analyzed (90.6%). Two patients were lost to follow-up, and 1 was excluded because of a postoperative hematoma. There were no statistically significant differences in postoperative pain, medication use, pain location, recovery room time, or mobility between the 2 study groups. CONCLUSION: There were comparable outcomes with 0.25% bupivacaine HCl at a 200-fold lower cost than liposomal bupivacaine. This study does not support the widespread use of liposomal bupivacaine for pain control after ACL reconstruction in the setting of a femoral nerve block. REGISTRATION: ClinicalTrials.gov NCT02189317.