Evaluation of the sealing function of the acetabular labrum: an in vitro biomechanical study.

PURPOSE: To quantitatively evaluate the biomechanical sealing function of an intact labrum and the effect of labral-chondral separation, cerclage suture labral repair, vertical mattress suture repair and partial labrectomy on distraction load and hip joint centre (HJC) displacement. METHODS: Eight fresh-frozen cadaveric hips were tested using a navigation system for intra-operative kinematic analysis. A six-axis load cell was used to measure the manually applied force when performing the tests: hip pivoting movement and distraction. The HJC displacement that occurred during the distraction test has been evaluated in correspondence of seven different values of applied force. During the pivoting motion, the maximum value of HJC displacement was evaluated. Five different conditions were tested: labrum intact, labral-chondral separation, vertical mattress suture repair, cerclage suture repair, and partial labrectomy. RESULTS: With regard to HJC displacement using at fixed value of force, the paired sample t test underscored the statistically significant differences (p < 0.05) for each of the five tested conditions among themselves. Only the comparison of intact versus labral-chondral separation was not significantly different. During pivoting motion, a statistically significantly greater displacement was identified after labrectomy when compared with the cerclage suture repair (p = 0.03) and vertical mattress repair (p < 0.01) in medial-lateral direction. Along proximal-distal direction, a significant lower displacement after labrectomy was identified when compared to the cerclage suture repair (p = 0.03). Performing the pivoting motion at the extreme ranges of motion demonstrated a higher value of displacement after labrectomy when compared with all the previously tested conditions. CONCLUSIONS: These results suggest that labral repair is important in the function of the hip and that the vertical mattress suture technique may be better than the cerclage suture repair.

Kinematics of ACL and anterolateral ligament. Part I: Combined lesion.

PURPOSE: To quantify the influence of ALL lesions on static and dynamic laxity in ACL-deficient knee. METHODS: The study was performed in 10 fresh-frozen knees. The joints were analysed in the following conditions: intact, ACL resection and ACL + ALL resection. Testing parameters were defined as: anterior displacement at 30° and 90° of flexion (AP30, AP90) applying a manual-maximum load; internal rotation at 30° and 90° of flexion (INT30, INT90) applying a 5 N m torque and internal rotation and acceleration during manual pivot-shift (PS) test. Kinematics was acquired by a navigation system; a testing rig and a torquemeter were used to control the limb position and the applied torque. Paired Student's t test was conducted to assess statistical difference, and significance was set at P < 0.05. RESULTS: The ALL resection determined a significant increase in terms of internal rotation (INT30 P = 0.02, INT90 P = 0.03), while AP30 (P n.s) and AP90 (P n.s) were not affected. ALL resection produced a significant increase in terms of acceleration during PS test (P < 0.01), but no significant change in PS internal rotation was observed. CONCLUSION: The ALL plays a significant role in controlling static internal rotation and acceleration during PS test. On the other hand, ALL resection did not produce any significant change in terms of anterior displacement. A trend was seen for the internal rotation during the pivot-shift test to increase after ALL resection was higher when compared to the intact and isolated ACL lesion states; however, the differences were not significant. The results highlight the clinical relevance of this structure that should be assessed before an ACL reconstruction in order to avoid residual laxity.

Kinematics of ACL and anterolateral ligament. Part II: anterolateral and anterior cruciate ligament reconstruction.

PURPOSE: To quantify the influence of Single-Bundle with Lateral Plasty and Double-Bundle reconstruction on static and dynamic laxity in combined ACL- and ALL-deficient knees. METHODS: The study included 10 fresh-frozen human knees. The joints were analyzed in the following conditions: ACL + ALL resection, Single-Bundle with Lateral Plasty (SBLP) reconstruction, Double-Bundle (DB) reconstruction. Testing parameters were: anterior displacement at 30° and 90° of flexion (AP30, AP90) applying a manual maximum load; internal rotation at 30° and 90° of flexion (INT30, INT90) applying a 5 Nm torque and acceleration and internal rotation Pivot-Shift (PS) test. Kinematics was acquired by a navigation system. Paired Student's t test was conducted to assess statistical difference (P < 0.05). RESULTS: At both 30° and 90° of knee flexion, both SBLP and DB surgical techniques showed a significant reduction (P < 0.01) of anterior-posterior tibial displacement compared to the resection of ACL + ALL. At 30° on knee flexion it is the SBLP that allows the greatest reduction of internal rotational laxity when compared to DB reconstruction. Concerning the PS test, only SBPL procedure had a significant laxity decrease considering the acceleration reached by the joint when compared with the ACL + ALL state (P < 0.01). CONCLUSION: Clinical relevance of this study is that the internal rotation and PS test were more efficiently controlled by the SBLP technique than by the DB one at both 30° and 90° of flexion in case of ACL + ALL lesions.

ACL rupture and joint laxity progression: a quantitative in vivo analysis.

PURPOSE: Benefits of an early reconstruction and the optimal time lapse between injury and surgery to reduce the effects of altered kinematics in ACL-deficient knees are still controversial. AIM: The aim of this study was to clarify, through a quantitative in vivo evaluation, the effects of the time lapse between ACL injury and surgery in terms of changes in the pre-operative knee laxity. METHODS: An in vivo study was performed on 99 patients who underwent ACL surgery. Just before the graft fixation, six laxity tests were performed for all the subjects at manual-maximum load: anterior-posterior displacement and internal-external rotation at 30° and 90° of knee flexion (AP30, AP90, IE30, IE90) as well as varus-valgus rotation (VV0, VV30) at 0° and 30° of flexion. Kinematics data were acquired by a navigation system. The Spearman rank correlation was used to assess correlation between rank and continuous data. Significance was set at P = 0.05. RESULTS: The analysis highlighted a significant influence of the injury-to-surgery time lapse on VV0 and AP90 compared with pre-operative laxity levels. Meniscus status also significantly affected the pre-operative laxity in the VV0 (Spearman's ρ = 0.203, P = 0.038; GLM with meniscal correction partial Î· = 0.27, P = 0.007) and AP90 (Spearman's ρ = 0.329, P = 0.001; GLM with meniscal correction partial Î· = 0.318, P = 0.017) tests. CONCLUSION: The main finding of this study is that patients with ACL rupture and a higher injury-to-surgery time present higher values of knee laxity involving AP90 displacement and VV30 rotation. Clinical relevance of the study is that ACL-deficient joint laxity, involving anterior-posterior displacement at 90° of knee flexion and varus-valgus rotation at 0° of flexion, is significantly affected by the lapse of injury-to-surgery time. This highlights the importance of considering the effects of delaying surgery when managing patients with such deficiency.

Does meniscus removal affect ACL-deficient knee laxity? An in vivo study.

PURPOSE: The purpose of the present study was to determine, in vivo, the effect of different types of meniscectomy on an ACL-deficient knee. METHODS: Using a computer-assisted navigation system, 56 consecutive patients (45 men and 11 women) were subjected to a biomechanical testing with Lachman test (AP30), drawer test (AP90), internal/external rotation test, varus/valgus rotation test and pivot-shift test. The patients were divided into three groups according to the status of the medial meniscus. Group BH, 8 patients with bucket-handle tear of medial meniscus underwent a subtotal meniscectomy; Group PHB, 19 patients with posterior horn body of medial meniscus tear underwent a partial meniscectomy; and Group CG with isolated ACL rupture, as a control group, with 29 patients. RESULTS: A significant difference in anterior tibial translation was seen at 30 grades and in 90 grades between BH and PHB groups compared to the CG. In response to pivot-shift test, no significant differences in terms of AREA and POSTERIOR ACC were found among the three groups (n.s). Concerning the anterior displacement of the pivot shift a statistically significant differences among the three tested groups was found. CONCLUSION: The present study shows that meniscal defects significantly affect the kinematics of an ACL-deficient knee in terms of anterior tibial translation under static and dynamic testing.

Current use of navigation system in ACL surgery: a historical review.

PURPOSE: The present review aims to analyse the available literature regarding the use of navigation systems in ACL reconstructive surgery underling the evolution during the years. METHODS: A research of indexed scientific papers was performed on PubMed and Cochrane Library database. The research was performed in December 2015 with no publication year restriction. Only English-written papers and related to the terms ACL, NAVIGATION, CAOS and CAS were considered. Two reviewers independently selected only those manuscripts that presented at least the application of navigation system for ACL reconstructive surgery. RESULTS: One hundred and forty-six of 394 articles were finally selected. In this analysis, it was possible to review the main uses of navigation system in ACL surgery including tunnel positioning for primary and revision surgery and kinematic assessment of knee laxity before and after different surgical procedures. In the early years, until 2006, navigation system was mainly used to improve tunnel positioning, but since the last decade, this tool has been principally used for kinematics evaluation. Increased accuracy of tunnel placement was observed using navigation surgery, especially, regarding femoral, 42 of 146 articles used navigation to guide tunnel positioning. During the following years, 82 of 146 articles have used navigation system to evaluate intraoperative knee kinematic. In particular, the importance of controlling rotatory laxity to achieve better surgical outcomes has been underlined. CONLUSIONS: Several applications have been described and despite the contribution of navigation systems, its potential uses and theoretical advantages, there are still controversies about its clinical benefit. The present papers summarize the most relevant studies that have used navigation system in ACL reconstruction. In particular, the analysis identified four main applications of the navigation systems during ACL reconstructive surgery have been identified: (1) technical assistance for tunnel placement; (2) improvement in knowledge of the kinematic behaviour of ACL and other structures; (3) comparison of effectiveness of different surgical techniques in controlling laxities; (4) navigation system performance to improve the outcomes of ACL reconstruction and cost-effectiveness. LEVEL OF EVIDENCE: IV.

Technical variables of ACL surgical reconstruction: effect on post-operative static laxity and clinical implication.

PURPOSE: The hypothesis was that an alteration of different surgical variables of ACL reconstruction would produce significant changes in post-operative static laxity of knee joint. METHODS: Joint laxity was acquired by a surgical navigation system for 17 patients just after graft fixation during single-bundle reconstruction with extra-articular lateral tenodesis. The analysed laxity parameters were: internal/external rotation at 30° (IE30) and 90° (IE90) of flexion, varus/valgus rotation at 0° (VV0) and 30° (VV30) of flexion and anterior/posterior displacement at 30° (AP30) and 90° (AP90) of flexion. As surgical variables, the angles between the tibial tunnel and the three planes were defined as well as the lengths of the tunnel and the relationship between native footprints and tunnels. The same analysis was performed for the femoral side. All surgical variables were combined in a multivariate analysis to assess for predictive factors between them and post-operative laxities values. To quantify the performance of each multivariate model, the correlation ratio (η 2) and the corresponding P value (*P < 0.050) have been evaluated. RESULTS: Multivariate analysis underlined statistically significant models for the estimation of: AP30 (η 2 = 0.987; P = 0.014), IE30 (η 2 = 0.995; P = 0.005), IE90 (η 2 = 0.568; P = 0.010), VV0 (η 2 = 0.932; P = 0.003). The parameters that greatly affected the identified models were the orientation of the tibial tunnel with respect to the three anatomical planes. The estimation of AP30, IE30 and IE90 got lower value as the orientation of the tibial tunnel with respect to transverse plane decreases. Considering the orientation to sagittal ([Formula: see text]) and coronal ([Formula: see text]) plane, we found that their reduction provoked a decrease in the estimation of AP30, IE30 and IE90 (except [Formula: see text] that did not appear in the estimation of AP30). The estimation of VV0 got an increase of [Formula: see text], and [Formula: see text] which led to a laxity reduction. CONCLUSION: The main finding of the present in vivo study was the possibility to determine significant effects on post-operative static laxity level of different surgical variables of ACL reconstruction. In particular, the present study defined the conditions that minimize the different aspects of post-operative laxity at time-zero after surgery.

Do pre-operative knee laxity values influence post-operative ones after anterior cruciate ligament reconstruction?

The objective of this study was to verify whether pre-reconstruction laxity condition effects post-reconstruction outcome. A total of 100 patients who underwent navigated Anterior Cruciate Ligament (ACL) reconstruction were included in the study and knee laxity analysed retrospectively. The knee was assessed in six different laxity tests before and after ACL reconstruction, namely antero-posterior (AP) and internal-external (IE) at 30° and 90°, and varus-valgus (VV) rotations at 0° and 30° of flexion. For each test, the least square (LS) fitting line based on pre-operative-to-post-operative laxity value was calculated. To what degree the post-operative laxity value is explainable by the corresponding pre-operative condition was evaluated by the LS line slope. Post-operatively, for each single patient, the grade of laxity decreased at any evaluated test. The strongest influence of pre-operative-to-post-operative laxity values was found during IE30 and IE90 tests. While AP30 and VV0 tests seem to be those in which the post-reconstruction laxity was barely affected by the pre-surgery condition. The analysis of the global laxity reduction confirms the previous results. Following this hypothesis, our study remarks on the importance of combined lesions to secondary restraints and the importance of fully understanding the residual laxity to optimize the surgical technique.

Unicompartmental osteoarthritis: an integrated biomechanical and biological approach as alternative to metal resurfacing.

PURPOSE: Although traditionally not indicated for the treatment of osteoarthritis (OA), regenerative procedures are becoming a focus of increased interest due to their potential to provide pain relief and alter the progression of degenerative diseases. The purpose of this study was to assess whether a combined biomechanical and biological approach could offer good results in unicompartmental OA, thus delaying the need for unicompartmental arthroplasty in patients too young or refusing metal resurfacing. METHODS: Forty-three patients (mean age = 40.1 ± 11 years, 33 men and 10 women, mean BMI = 25 ± 3) affected by unicompartmental OA (Kellegren-Lawrence score = 3) in stable joints were enrolled and treated consecutively. Fifteen patients were treated with osteotomy and osteochondral biomimetic scaffold implant (3 of them also with meniscal substitution), 11 with osteotomy and meniscal scaffold implant, 9 with osteotomy and meniscal allograft implant, and 8 with both cartilage and meniscal reconstruction, depending on the specific joint compartment main requirements. Clinical evaluation was performed at 3-year (2-4) median follow-up using the following scoring systems: IKDC subjective and objective, VAS for pain, and Tegner scores. Failures, adverse events, and complications were also reported. RESULTS: The IKDC subjective score improved from 47.3 to 79.6 at the final evaluation (p < 0.0005), VAS improved from 6.1 to 2.3 (p < 0.0005), and also sport activity level evaluated with the Tegner score showed a significant improvement, from 2 (1-5) to 4 (3-10; p < 0.0005), even if without achieving the pre-injury level (6, p = 0.001). A further subanalysis confirmed the positive outcome obtained in all the treatment subgroups and showed a higher clinical improvement in patients under the age of 40 years (IKDC subjective 84.4 ± 13.2 vs 76.5 ± 17.3; p = 0.03). CONCLUSION: This integrated biological and biomechanical approach produced a marked improvement at short-medium follow-up in patients affected by unicompartmental OA. Even though a good outcome was achieved at all ages, patients under the age of 40 years presented a greater clinical and subjective improvement. Longer follow-up studies are needed to show results over time and confirm this approach as an effective alternative to unicompartmental implants.

Anatomic double-bundle and over-the-top single-bundle with additional extra-articular tenodesis: an in vivo quantitative assessment of knee laxity in two different ACL reconstructions.

PURPOSE: Combinations of intra- and extra-articular procedures have been proposed for anterior cruciate ligament reconstruction with the aim of achieving an optimal control of translational and rotational knee laxities. Recently, the need for better reproducing the structural and functional behavior of the native anterior cruciate ligament led to the definition of anatomic double-bundle surgical approach. This study aimed to quantitatively verify whether the in vivo static and dynamic behavior obtained using over-the-top single-bundle with extra-articular tenodesis reconstruction was comparable to the results achieved by anatomic double-bundle approach. METHODS: Thirty-five consecutive patients, with an isolated anterior cruciate ligament injury, were included in the study. Standard clinical laxities and pivot-shift test were quantified before and after anterior cruciate ligament reconstruction by means of a surgical navigation system dedicated to kinematic assessment; displacements of medial and lateral compartment during stress tests were also analyzed. RESULTS: Single-bundle with extra-articular tenodesis approach presented statistically better laxity reduction in varus/valgus stress test at full extension and in internal/external rotation at 90° of flexion; lateral plasty controlled better the lateral compartment during drawer test and varus/valgus stress test both at 0° and 30° of flexion and both the compartments during internal/external rotation at 90° of flexion. On the other hand, pivot-shift phenomenon was better controlled by anatomic double-bundle reconstruction. CONCLUSIONS: Both the reconstructions worked similarly for static knee laxity. The extra-articular procedure played an important role in better constraining the displacement of lateral tibial compartment, whereas the anatomic double-bundle reconstruction better restored the dynamic behavior of knee joint highlighted under pivot-shift stress test. STUDY DESIGN: Case series.

Predictive mathematical modeling of knee static laxity after ACL reconstruction: in vivo analysis.

Previous studies did not take into consideration such large variety of surgery variables which describe the performed anterior cruciate ligament (ACL) reconstruction and the interaction among them in the definition of postoperative outcome. Seventeen patients who underwent navigated Single Bundle plus Lateral Plasty ACL reconstruction were enrolled in the study. Static laxity was evaluated as the value of anterior/posterior displacement at 30° and at 90° of flexion, internal/external rotation at 30° and 90° of knee flexion, varus/valgus test at 0° and 30° of flexion. The evaluated surgical variables were analyzed through a multivariate analysis defining the following models: AP30estimate, AP90estimate, IE30estimate, IE90estimate, VV0estimate, VV30estimate. Surgical variables has been defined as the angles between the tibial tunnel and the three planes, the lengths of the tunnel and the relationship between native footprints and tunnels. An analogous characterization was performed for the femoral side. Performance and significance of the defined models have been quantified by the correlation ratio (η(2)) and the corresponding p-value (*p < 0.050). The analyzed models resulted to be statistically significant (p < 0.05) for prediction of postoperative static laxity values. The only exception was the AP90estimate model. The η(2) ranged from 0.568 (IE90estimate) to 0.995 (IE30estimate). The orientation of the tibial tunnel resulted to be the most important surgical variable for the performed laxity estimation. Mathematical models for postoperative knee laxity is a useful tool to evaluate the effects of different surgical variables on the postoperative outcome.

Conservative treatment of spontaneous osteonecrosis of the knee in the early stage: pulsed electromagnetic fields therapy.

HYPOTHESIS: pulsed electromagnetic fields treatment might improve symptoms in the early stage of spontaneous osteonecrosis of the knee. METHODS: Twenty-eight patients (19M/9F, age 49.8±16.4 years) suffering from symptomatic (pain) Koshino stage I spontaneous osteonecrosis of the knee, confirmed by magnetic resonance imaging (MRI) were treated with local pulsed electromagnetic fields therapy (6 h daily for 90 days). Clinical evaluation: baseline, 6- and 24-month follow-up by VAS for pain, knee society score (KSS), Tegner and EQ-5D scales. MRI evaluation: baseline and 6-month follow-up, measuring bone marrow lesion's areas and grading these lesions by WORMS score. Failures: patients undergoing knee arthroplasty. RESULTS: Pain significantly reduced at 6 months (from 73.2±20.7 to 29.6±21.3, p<0.0001), which remained almost unchanged at final follow-up (27.0±25.1). KSS significantly increased in first 6 months (from 34.0±13.3 to 76.1±15.9, p<0.0001) and was slightly reduced at final follow-up (72.5±13.5, p=0.0044). Tegner median level increased from baseline to 6-month follow-up (1(1-1) and 3(3-4), respectively, p<0.0001) and remained stable. EQ-5D improved significantly throughout the 24 months (0.32±0.33, baseline; 0.74±0.23, 6-month follow-up (p<0.0001); 0.86±0.15, 24-month follow-up (p=0.0071)). MRI evaluation: significant reduction of total WORMS mean score (p<0.0001) and mean femoral bone marrow lesion's area (p<0.05). This area reduction was present in 85% and was correlated to WORMS grading both for femur, tibia and total joint (p<0.05). Four failures (14.3%) at 24-month follow-up. CONCLUSIONS: Pulsed electromagnetic fields stimulation significantly reduced knee pain and necrosis area in Koshino stage I spontaneous osteonecrosis of the knee already in the first 6 months, preserving 86% of knees from prosthetic surgery at 24-month follow-up. No correlation was found between MRI and clinical scores. LEVEL OF EVIDENCE: Level IV; case series.

Does chronic medial collateral ligament laxity influence the outcome of anterior cruciate ligament reconstruction?: a prospective evaluation with a minimum three-year follow-up.

We have shown in a previous study that patients with combined lesions of the anterior cruciate (ACL) and medial collateral ligaments (MCL) had similar anteroposterior (AP) but greater valgus laxity at 30° after reconstruction of the ACL when compared with patients who had undergone reconstruction of an isolated ACL injury. The present study investigated the same cohort of patients after a minimum of three years to evaluate whether the residual valgus laxity led to a poorer clinical outcome. Each patient had undergone an arthroscopic double-bundle ACL reconstruction using a semitendinosus-gracilis graft. In the combined ACL/MCL injury group, the grade II medial collateral ligament injury was not treated. At follow-up, AP laxity was measured using a KT-2000 arthrometer, while valgus laxity was evaluated with Telos valgus stress radiographs and compared with the uninjured knee. We evaluated clinical outcome scores, muscle girth and time to return to activities for the two groups. Valgus stress radiographs showed statistically significant greater mean medial joint opening in the reconstructed compared with the uninjured knees (1.7 mm (SD 0.9) versus 0.9 mm (SD 0.7), respectively, p = 0.013), while no statistically significant difference was found between the AP laxity and the other clinical parameters. Our results show that the residual valgus laxity does not affect AP laxity significantly at a minimum follow up of three years, suggesting that no additional surgical procedure is needed for the medial collateral ligament in combined lesions.