Anterior Cruciate Ligament-Injured Knees With Meniscal Ramp Lesions Manifest Greater Anteroposterior and Rotatory Instability Compared With Isolated Anterior Cruciate Ligament-Injured Knees.

PURPOSE: To investigate the effects of ramp lesion (RL) and its repair on knee instability in patients with anterior cruciate ligament (ACL) injury by quantitatively assessing anteroposterior and rotational knee instability before and after ACL reconstruction. METHODS: All primary double-bundle ACL reconstructions using hamstring autografts between 2016 and 2021 were evaluated retrospectively. Patients with RLs without other meniscal injuries were included in group R, whereas those with isolated ACL injuries constituted group C. RL was repaired using all-inside devices in all patients in group R. Knee instability, including the amount of anterior tibial translation (ATT), and the acceleration and external rotational angular velocity of the knee joint (ERAV) during the pivot-shift test were assessed at the time of surgery. The pivot-shift test grade was recorded. RESULTS: A total of 73 patients were included in this study. Preoperatively, group R (n = 23) had significantly greater pivot-shift grades (P = .039), ATT (6.0 mm, group R; 4.5 mm, group C, P < .001), acceleration (6.8, 2.8; P = .037), and ERAV (3.9, 2.8; P = .001) than group C (n = 50). Intraoperatively, ATT (-1.0 mm, -1.0 mm; P < .001), acceleration (1.2, 1.1; P < .001), and ERAV (1.4, 1.2; P < .001) were significantly decreased compared with the preoperative values in both groups. No significant differences in these values were observed between groups R and C. CONCLUSIONS: ACL-injured knees accompanied by RLs exhibited significantly greater anteroposterior and rotatory instability than knees with isolated ACL injuries; increased knee instability can be effectively addressed by performing RL repair in conjunction with ACL reconstruction. The quantitative assessments employed-specifically measuring ATT, acceleration, and ERAV during the pivot-shift test-have allowed us to delineate these aspects of knee instability with greater precision. LEVEL OF EVIDENCE: Level Ⅲ, retrospective comparative study.

Constitutional varus knee due to tibial deformity is common and represents a good indication for high tibial osteotomy in Japanese population: Consideration of 1010 knees.

PURPOSE: This study aimed to elucidate the characteristics of varus knee deformities in the Japanese population, prevalence of various around knee osteotomy procedures and influence of femoral and tibial bowing. METHODS: Varus knee deformity was defined as a weight-bearing line ratio of <50%. A total of 1010 varus knees were selected from 1814 varus knees with weight-bearing full-length radiographs, obtained at two facilities, based on exclusion criteria. Various parameters were measured, and around knee osteotomy simulations based on the deformity centre were conducted using digital planning tools. Bowing of the femoral and tibial shafts was measured, with bowing defined as follows: ≤ -0.6° indicating lateral bowing and ≥ 0.6° indicating medial bowing. Statistical analysis was performed to investigate age-related correlations and their impact on surgical techniques. RESULTS: The study revealed that the proximal tibia was the centre of deformity in Japanese varus knees (42.8%), and high tibial osteotomy was frequently indicated (81.6%). Age demonstrated a mild correlation with femoral shaft bowing (r = -0.29), leading to an increase in the mechanical lateral distal femoral angle and to a decrease in the hip-knee-ankle angle and weight-bearing line ratio (r = -0.29, 0.221, 0.219). The tibial shaft bowing was unaffected by age (r = -0.022). CONCLUSION: A significant proportion of Japanese individuals with varus knees exhibit a deformity centre located in the proximal tibia, making them suitable candidates for high tibial osteotomy. No age-related alterations were discerned in tibial morphology, indicating that the occurrence of constitutional varus knees is attributable to tibial deformities in the Japanese patient cohort. LEVEL OF EVIDENCE: Level IV.

Efficacy of all-inside devices in reducing gap and step-off in knee extension for ramp lesion repair: A cadaveric study.

PURPOSE: The aim of this study is to assess the dynamics of the tear site of meniscal ramp lesions, particularly considering knee flexion angles, and validate anchor fixation using an all-inside device. METHODS: Eight Thiel-embalmed paired cadaveric knees with their whole bodies were used in this study. The ramp lesions were created arthroscopically, and ramp lesion dynamics were evaluated by gradually extending the knee from 90° of knee flexion. Changes in the gap and step-off (0: no step-off; 1: cross-sectional overlap exists; and 2: tibial articular surface exposed) were evaluated at 90°, 60°, 30°, and 10° of knee flexion. After dynamic evaluation, all-inside repairs of the ramp lesions using all-inside devices were conducted. Dissection was performed to confirm the position of anchor fixation. RESULTS: As the knee was extended, the gap significantly decreased at all knee flexion angles. Similarly, the step-off grade decreased as the knee was extended, and the step-off completely disappeared in all cases when the knee was extended from 30° to 10°. The average knee flexion angle at which the gap and step-off completely disappeared was 22.5°. After suturing the ramp lesion, arthroscopic evaluation showed that the gap had disappeared and the step-off had been repaired in all cases. Anchor fixation locations were not found within the joint but were fixed to the semimembranosus tendon or its surrounding articular capsule. Overall, 31% (5/16) anchors were fixed to the attachment site of the semimembranosus tendon, whereas the remaining were fixed to the articular capsule, located peripherally to the semimembranosus tendon. CONCLUSION: Suturing with an all-inside device for ramp lesions is a good option, and the repair in knee extension was found to be reasonable, considering the dynamics of ramp lesions in this study. LEVEL OF EVIDENCE: Level IV.

Diagnosis of medial meniscal ramp lesion is difficult by pre-operative magnetic resonance imaging evaluation and needs a methodical arthroscopic exploration.

BACKGROUND: Meniscal ramp lesion (RL) is the peripheral lesion of the posterior horn of the medial meniscus (PHMM) associated with anterior cruciate ligament (ACL) tear. The purpose of this study was to evaluate the accuracy of pre-operative magnetic resonance imaging (MRI) evaluation in diagnosing RL and to identify whether the difficulty in diagnosis differs depending on the location of RL. METHODS: ACL-injured patients undergoing ACL reconstruction from January 2017 to January 2019 were enrolled. A methodical arthroscopic exploration to identify RL was conducted intra-operatively using three steps, namely, the anterior visualization step, the inter-condylar visualization step, and the posteromedial step. The location of the RLs was evaluated and classified into two types as follows: Red-red zone (RR) - a meniscal tear of the red-red zone of the PHMM. Menisco-capsular junction (MCJ) - a lesion at the menisco-capsular junction of the PHMM, which is more peripheral than RR. Furthermore, the accuracy of 1.5-T MRI evaluation to diagnose RL by two testers using sagittal proton-density fat-saturated images was calculated. RESULTS: Of the 81 patients enrolled, 11 had RL: 5 cases each were at the MCJ and RR, and 1 case was at both locations. The sensitivity of MRI for detecting RL was 27.3-45.5%, whereas the specificity was 84.3-95.7% in total. The sensitivity of MRI in detecting RL at the RR and MCJ was 40.0-80.0%, 0-20.0%, respectively. The intra-observer reliability of the MRI evaluation was moderate (κ coefficient: 0.40-0.46), while the inter-observer reliability was fair to moderate (κ coefficient: 0.27-0.41). CONCLUSIONS: A low sensitivity of the MRI in detecting RL at the MCJ was observed, and the reliability of the MRI evaluation for diagnosis of RL was not high. Therefore, methodical arthroscopic exploration is essential to diagnose RL even when it is not suspected on pre-operative MRI.

Phylogenetic composition of host plant communities drives plant-herbivore food web structure.

Insects tend to feed on related hosts. The phylogenetic composition of host plant communities thus plays a prominent role in determining insect specialization, food web structure, and diversity. Previous studies showed a high preference of insect herbivores for congeneric and confamilial hosts suggesting that some levels of host plant relationships may play more prominent role that others. We aim to quantify the effects of host phylogeny on the structure of quantitative plant-herbivore food webs. Further, we identify specific patterns in three insect guilds with different life histories and discuss the role of host plant phylogeny in maintaining their diversity. We studied herbivore assemblages in three temperate forests in Japan and the Czech Republic. Sampling from a canopy crane, a cherry picker and felled trees allowed a complete census of plant-herbivore interactions within three 0·1 ha plots for leaf chewing larvae, miners, and gallers. We analyzed the effects of host phylogeny by comparing the observed food webs with randomized models of host selection. Larval leaf chewers exhibited high generality at all three sites, whereas gallers and miners were almost exclusively monophagous. Leaf chewer generality dropped rapidly when older host lineages (5-80 myr) were collated into a single lineage but only decreased slightly when the most closely related congeneric hosts were collated. This shows that leaf chewer generality has been maintained by feeding on confamilial hosts while only a few herbivores were shared between more distant plant lineages and, surprisingly, between some congeneric hosts. In contrast, miner and galler generality was maintained mainly by the terminal nodes of the host phylogeny and dropped immediately after collating congeneric hosts into single lineages. We show that not all levels of host plant phylogeny are equal in their effect on structuring plant-herbivore food webs. In the case of generalist guilds, it is the phylogeny of deeper plant lineages that drives the food web structure whereas the terminal relationships play minor roles. In contrast, the specialization and abundance of monophagous guilds are affected mainly by the terminal parts of the plant phylogeny and do not generally reflect deeper host phylogeny.

Isolation and characterization of SSEA-4-positive subpopulation of human deciduous dental pulp cells.

OBJECTIVES: It is well accepted that stage-specific embryonic antigen (SSEA)-4 is an antigen that is useful to isolate adult stem cells analogous to embryonic stem cells. Therefore, in the present study, we investigated whether SSEA-4 can also be used as a marker to identify human deciduous dental pulp (D-DP) stem cells. MATERIALS AND METHODS: Intact deciduous teeth were collected from healthy patients who were undergoing orthodontic treatment at Okayama University Hospital. Immunofluorescence analysis, flow cytometric analysis, and multilineage differentiation assay were performed to characterize SSEA-4+ D-DP cells. RESULTS: The D-DP cells had the characteristics of mesenchymal stem cells (MSCs), namely plastic adherence, specific surface antigen expression, and multipotent differentiation potential. SSEA-4 expression was detected in D-DP cells in vitro and ex vivo samples. A flow cytometric analysis demonstrated that 21.2 % of the D-DP cells were positive for SSEA-4. The SSEA-4+ clonal D-DP cells showed multilineage differentiation potential toward adipocytes, osteoblasts, and chondrocytes in vitro. In fact, 26.1 % (6/23) of the SSEA-4+ clonal D-DP cells showed adipogenic potential, 91.3 % (21/23) showed osteogenic potential, 91.3 % (21/23) showed chondrogenic potential, and 87.0 % (20/23) showed both osteogenic and chondrogenic potential. CONCLUSIONS: Thus, the majority of SSEA-4+ D-DP cells had the potential for multilineage differentiation. Hence, SSEA-4 appears to be a specific marker that can be used to identify D-DP stem cells. CLINICAL RELEVANCE: SSEA-4+ D-DP cells appear to be a promising source of stem cells for regenerative therapy.

Factors Associated With Residual Pivot Shift After ACL Reconstruction: A Quantitative Evaluation of the Pivot-Shift Test Preoperatively and at Minimum 12-Month Follow-up.

Background: Postoperative residual rotatory laxity remains despite improvement in surgical techniques for anterior cruciate ligament (ACL) reconstruction (ACLR). Purpose: To evaluate factors associated with residual pivot shift after ACLR by quantitative measurement of the pivot shift before and after surgery. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 97 patients who underwent primary double-bundle ACLR between June 2016 and March 2021 and underwent surgery to remove staples, with at least 12 months of follow-up evaluation, were enrolled. Quantitative measurements were performed under general anesthesia immediately before ACLR (preoperatively), after temporary fixation of the ACL graft (intraoperatively), and immediately before staple removal (postoperatively). The laxity of pivot shift was assessed using inertial sensors to measure acceleration and external rotational angular velocity (ERAV). Descriptive data were assessed for associations with postoperative acceleration and ERAV in a univariate analysis. A multiple linear regression analysis was performed to identify factors associated with postoperative acceleration and ERAV. Results: Anterior tibial translation, acceleration, and ERAV increased from intra- to postoperatively (P < .05). Factors significantly associated with postoperative acceleration were age (ß = -0.238; P = .021), lateral posterior tibial slope (PTS) (ß = 0.194; P = .048), and preoperative acceleration (ß = 0.261; P = .008). Factors significantly affecting postoperative ERAV were age (ß = -0.222; P = .029), ramp lesions (ß = 0.212; P = .027), and preoperative ERAV (ß = 0.323; P = .001). Conclusion: Greater preoperative laxity in the pivot shift was the factor having the most significant association with residual pivot shift after ACLR using quantitative measurements under general anesthesia. Younger age, higher lateral PTS, and concomitant ramp lesions were significant predictors of residual pivot shift. These findings can help pre- and intraoperative decision-making regarding whether an anterolateral structure augmentation should be added.

Factors Associated with Return to Sport After Anterior Cruciate Ligament Reconstruction: A Focus on Athletes Who Desire Preinjury Level of Sport.

INTRODUCTION: In most previous studies investigating return to preinjury level of sport (RTPS) after anterior cruciate ligament reconstruction (ACLR), whether patients continue aiming for RTPS not only before but also after ACLR was unclear because environmental and social factors were not considered. Herein, we aimed to evaluate factors associated with RTPS among athletes who desired to achieve RTPS even after ACLR, excluding patients who no longer desire this goal owing to environmental and social factors. METHODS: Ninety-two patients who underwent primary double-bundle ACLR with a minimum 2-year follow-up and desired to achieve RTPS before surgery were retrospectively enrolled. Twelve (13%) patients who no longer desired to achieve RTPS after ACLR owing to environmental and social factors were excluded. Sixty-nine patients were included in the final cohort. At the final follow-up, the patients were split into two groups: those who achieved (R group) or did not achieve (N group) RTPS based on patient self-assessment. The Knee Injury and Osteoarthritis Outcome Score (KOOS) and Lysholm scores were also determined. The anterior tibial translation in the Lachman test and acceleration and external rotational angular velocity (ERAV) in the pivot shift test were measured at the hardware removal operation. RESULTS: Significant differences were observed for preinjury level of sports between the groups (p < 0.05). The rate of RTPS in competitive athletes was lower than that in recreational athletes (20/46: 43% vs. 16/22: 73%; p =.037). Lysholm score, KOOS symptom, pain, and quality of life showed higher values in the R group than in the N group (p < 0.050). Acceleration was significantly lower in the R group than in the N group (p = 0.028). CONCLUSION: Competitive level of sports is a risk factor for failure to achieve RTPS. The postoperative functional outcomes in the group that achieved RTPS showed more favorable results. These results provide important information to enable the surgeons to consider the appropriate surgical plan for competitive athletes who desire to achieve RTPS after ACLR.

Stage-specific embryonic antigen-4 identifies human dental pulp stem cells.

Embryonic stem cell-associated antigens are expressed in a variety of adult stem cells as well as embryonic stem cells. In the present study, we investigated whether stage-specific embryonic antigen (SSEA)-4 can be used to isolate dental pulp (DP) stem cells. DP cells showed plastic adherence, specific surface antigen expression, and multipotent differentiation potential, similar to mesenchymal stem cells (MSC). SSEA-4+ cells were found in cultured DP cells in vitro as well as in DP tissue in vivo. Flow cytometric analysis demonstrated that 45.5% of the DP cells were SSEA-4+. When the DP cells were cultured in the presence of all-trans-retinoic acid, marked downregulation of SSEA-3 and SSEA-4 and the upregulation of SSEA-1 were observed. SSEA-4+ DP cells showed a greater telomere length and a higher growth rate compared to ungated and SSEA-4- cells. A clonal assay demonstrated that 65.5% of the SSEA-4+ DP cells had osteogenic potential, and the SSEA-4+ clonal DP cells showed multilineage differentiation potential toward osteoblasts, chondrocytes, and neurons in vitro. In addition, the SSEA-4+ DP cells had the capacity to form ectopic bone in vivo. Thus, our results suggest that SSEA-4 is a specific cell surface antigen that can be used to identify DP stem cells.

An Analysis of the Femoral Drilling Angle to Avoid Tunnel Collision during Double-Bundle Anterior Cruciate Ligament and Anterolateral Ligament Reconstruction on the Knee.

Concomitant anterior cruciate ligament (ACL) and anterolateral ligament (ALL) reconstruction has been reported as an effective technique for providing rotational control of the knee. However, the intraoperative risk of collision with an ACL tunnel during the drilling for the femoral ALL tunnel has been described. The purpose of this study was to investigate the various femoral drilling procedures to avoid tunnel collisions during combined double-bundle ACL and ALL reconstruction. Nine cadaveric knees were used in this study. ACL drilling was performed through the anteromedial portal to footprints of the posterolateral bundle at 120° (PL120) and 135° (PL135) knee flexion and the anteromedial bundle at 120° (AM120) and 135° (AM135) knee flexion. ALL drilling was performed at 0° (Cor0-ALL) and 30° (Cor30-ALL) coronal angles using a Kirschner wire (K-wire). The distance between the ALL footprint and ACL K-wire outlets, axial angles of ALL K-wires colliding with ACL K-wires, and distances from the ALL footprint to the collision point were measured. From these values, the safe zone, defined as the range of axial angles in which no collisions or penetrations occurred, was identified by simulation of tunnels utilized for reconstruction grafts in each drilling procedure. The point-to-point distance from the ALL footprint to the K-wire outlet was significantly greater in the AM120 than the AM135 (13.5 ± 3.1, 10.8 ± 3.2 mm; p = 0.048) and in the PL135 than the PL120 (18.3 ± 5.5, 16.1 ± 6.5 mm; p = 0.005) conditions, respectively. During an ACL drilling combination of PL135/AM120, a safe zone of > 45° in Cor30-ALL was identified. With a narrow safe zone during the PL135/AM120 combination only, the risk of femoral tunnel collisions in combined double-bundle ACL and ALL reconstruction is high. AM drilling at 120° and PL drilling at > 135° knee flexion, combined with ALL drilling at 30° coronal angle and > 45° axial angle, may reduce this risk.

Comparison of Visibility and Risk of Neurovascular Tissue Injury Between Portals in Needle Arthroscopy of the Anterior Ankle Joint: A Cadaveric Study.

Background: For needle arthroscopy with 0° viewing, the visible range of intra-articular structures and the difference between portals remain unknown, as do the risks for neurovascular tissue at each portal. Purpose: To clarify the visibility and safety of needle arthroscopy. Study Design: Descriptive laboratory study. Methods: Ten cadaveric ankle specimens were used. A needle arthroscope with a 1.9-mm diameter was inserted from 4 portals (anteromedial [AM], anterolateral [AL], medial midline [MM], and anterocentral [AC]). Visibility was assessed using a 15-point ankle arthroscopy checklist. In addition, the ankles were dissected to measure the distance between each portal and neurovascular tissues. The visibility of the ankle joint was compared between portals. Results: The success rate of visibility in the deltoid ligament and the tip of the medial malleolus was 100% from the AM, MM, and AC portals and 10% from the AL portal, with significant differences between the portals (P < .01). The visibility success rates in the origin of the anterior talofibular ligament and the tip of the lateral malleolus were 20% for the AM portal, 90% for the MM and AC portals, and 100% for the AL portal, with significant differences between the portals (P < .01). All other points of the ankle joint were visualized from all the portals with a 100% success rate. The AC portal was in contact with the anterior neurovascular bundle in 4 of the 10 specimens. Conclusion: When needle arthroscopy was performed from the AM or AL portal, the site opposite to the portal in the ankle joint was difficult to visualize. Conversely, most points of the ankle joint could be visualized from the MM and AC portals. Care should be taken when creating an AC portal because of its proximity to the anterior neurovascular bundle. Clinical Relevance: The present study provides information regarding which portal should be selected to perform needle arthroscopy in the ankle joint, which will be beneficial for management of ankle injuries.

Ultrasound Assessment of Anterior Humeral Head Translation in Patients With Anterior Shoulder Instability: Correlation With Demographic, Radiographic, and Clinical Data.

Background: Ultrasonography can be used to quantitatively assess anterior humeral head translation (AHHT) at different degrees of shoulder abduction. Risk factors for recurrent shoulder instability have been identified. Hypothesis: It was hypothesized that the number of dislocations or glenoid or humeral bone loss would be associated with more AHHT as measured using ultrasound. Study Design: Cross-sectional study; Level of evidence, 3. Methods: A total of 39 patients who underwent surgery for anterior shoulder instability were prospectively studied. Ultrasound assessment of AHHT was performed immediately after general anesthesia was induced. The upper arm was placed at 0°, 45°, and 90° of abduction, and a 40-N anterior force was applied to the proximal third of the arm. The distance from the posterior edge of the glenoid to that of the humeral head was measured at each abduction angle using ultrasound with and without a 40-N anterior force, and the AHHT was calculated. The differences in translation at each shoulder angle were compared. Additionally, the authors investigated the association between AHHT and demographic, radiographic, and clinical data. Results: Compared with the AHHT at 0° of abduction (5.29 mm), translation was significantly larger at 45° of abduction (8.90 mm; P < .01) and 90° of abduction (9.46 mm; P < .01). The mean translation was significantly larger in female patients than in male patients at all degrees of abduction (P ≤ .036 for all). There was no correlation between AHHT at any abduction angle and number of dislocations, clinical data, or radiographic data (including bone loss). Conclusion: Ultrasound assessment of AHHT showed larger amounts of laxity at 45° and 90° than at 0° of abduction. Anterior glenohumeral laxity was greater in female than male patients. Glenoid or humeral bone loss did not correlate with AHHT, thereby clarifying that bone loss has no direct effect on measurements of capsular laxity in neutral rotation.

Ultrasonographic Assessment of Glenohumeral Joint Stability Immediately After Arthroscopic Bankart-Bristow Procedure.

Background: The changes in glenohumeral joint stability after surgery in a clinical setting are yet unknown. Purpose/Hypothesis: This study aimed to compare the anterior humeral head translation between pre- and postsurgical conditions using ultrasonography. It was hypothesized that ultrasonographic assessment would reveal decreased anterior translation. Study Design: Case series; Level of evidence, 4. Methods: A total of 27 patients (24 male, 3 female; mean age, 24.1 ± 9.7 years) with anterior shoulder instability were studied prospectively. All the patients underwent the arthroscopic Bankart-Bristow procedure under general anesthesia, and ultrasonographic evaluation was performed before and immediately after surgery. The forearm was fixed with an arm positioner in the beach-chair position, and the ultrasonographic transducer was located at the posterior part of the shoulder to visualize the humeral head and glenoid rim at the level of interval between the infraspinatus tendon and teres minor tendon. The upper arm was drawn anteriorly with a 40-N force at 0°, 45°, and 90° of shoulder abduction with neutral rotation. The distance from the posterior edge of the glenoid to that of the humeral head was measured using ultrasonography with and without anterior force. Anterior translation was defined by subtracting the distance with anterior force from the distance without anterior force. Results: The humeral head position was translated posteriorly immediately after surgery in all patients. Anterior translation decreased significantly after surgery at 45° (7.7 ± 4.3 vs 5.8 ± 2.0 mm; P = .031) and 90° (8.9 ± 3.4 vs 6.1 ± 2.2 mm; P < .001) of abduction, whereas there was no difference between pre- and postsurgical translation at 0° of abduction (4.9 ± 2.3 vs 4.0 ± 2.1 mm, P = .089). Conclusion: Ultrasonographic assessment immediately after a Bankart-Bristow procedure showed the humeral head was translated posteriorly relative to the glenoid at 0°, 45°, and 90° of abduction. The surgery also decreased anterior translation in response to an anteriorly directed force at 45° and 90° of abduction.

Anterolateral ligament reconstruction in addition to primary double-bundle anterior cruciate ligament reconstruction for grade 3 pivot shift improves residual knee instability during surgery.

PURPOSE: High-grade pivot shift in the anterior cruciate ligament (ACL) injured knee is a risk factor for postoperative residual pivot shift. Procedures in addition to ACL reconstruction such as anterolateral ligament (ALL) reconstruction have been performed for patients with a high-risk of residual pivot shift. The aim of this study was to investigate the effect of the addition of ALL reconstruction to primary double-bundle ACL reconstruction in patients with preoperative high-grade pivot shift to improve stability as evaluated by quantitative measurement. METHODS: Patients with ACL injuries who showed preoperative grade 3 subjective pivot shift and who underwent primary double-bundle ACL reconstruction combined with ALL reconstructions were retrospectively enrolled. Anterior tibial translation (ATT) in the Lachman test, and acceleration and external rotational angular velocity (ERAV) in the pivot shift were measured as quantitative values. Quantitative values before surgical intervention for ACL-injured knees (ACLD) and uninjured contralateral knees (intact), after temporary fixation of the isolated ACL grafts (ACLR), and subsequently after temporary fixation of both ACL and ALL grafts (ACLR + ALLR) were measured with the patient under general anaesthesia. RESULTS: In total, 18 patients were included. The ATT was lower in ACLR and ACLR + ALLR than in intact (P = .008 and .005), while there was no significant difference between ACLR and ACLR + ALLR (P > .05). The acceleration of ACLR + ALLR was lower than that for ACLR (P = .008), while there was no significant difference between intact and ACLR or ACLR + ALLR (P > .05). The ERAV of ACLR was higher than that of intact (P < .001), while that of ACLR + ALLR was lower than that of ACLR (P < 0.001), and there was no significant difference in ERAV between intact and ACLR + ALLR (P > 0.05). CONCLUSION: According to quantitative assessment of the pivot shift, the addition of ALL reconstruction to primary double-bundle ACL reconstruction improved residual knee instability and restored knee stability during surgery. Combination of ALL reconstruction with primary double-bundle ACL reconstruction was effective for patients with ACL injuries exhibiting a preoperative grade 3 subjective pivot shift. LEVEL OF EVIDENCE: IV.

Preoperative Knee Instability Affects Residual Instability as Evaluated by Quantitative Pivot-Shift Measurements During Double-Bundle ACL Reconstruction.

BACKGROUND: The pivot-shift test is an important indicator of functional outcomes after anterior cruciate ligament (ACL) reconstruction (ACLR). Preoperative instability as indicated by the pivot-shift test is associated with residual instability after ACLR. Few studies have used quantitative means to evaluate the pivot shift after ACLR. PURPOSE: To investigate the relationship between preoperative and residual instability and to identify the risk factors for residual instability by using quantitative measurements of the pivot shift. STUDY DESIGN: Case-control study; Level of evidence, 3. METHODS: A total of 91 patients undergoing primary double-bundle ACLR were retrospectively enrolled. Quantitative measurements of instability for ACL-deficient knees (ACLD) and uninjured contralateral knees (intact) preoperatively, as well as ACLR knees intraoperatively, were performed under general anesthesia using the pivot-shift test, with inertial sensors to measure acceleration and external rotational (ER) angular velocity. The ratios of intact to ACLD (ACLD/I) and intact to ACLR (ACLR/I) were measured. Patients who showed an ACLR/I of >1 were classified into the residual instability group, and those with an ACLR/I of ≤1 were classified into the noninstability group. Regarding demographic, surgical, and quantitative measurement factors, between-group comparisons and multivariate logistic regression were conducted for predictors of residual instability. Receiver operating characteristic curves were used to evaluate the correlations between ACLD/I and ACLR/I and the cutoff value of ACLD/I in predicting residual instability. RESULTS: The predictive factors for intraoperative residual instability included female sex (odds ratio [OR], 0.3 [95% CI, 0.1-0.9]; P = .034) and ACLD/I for acceleration (OR, 1.6 [95% CI, 1.2-2.1]; P < .001), and ACLD/I for ER angular velocity (OR, 1.9 [95% CI, 1.2-3.1]; P = .013). Correlations between ACLD/I and ACLR/I were moderate with respect to both acceleration (r = 0.435; P < .001) and ER angular velocity (r = 0.533; P < .001). The cutoff points for ACLD/I were 4.9 for acceleration (sensitivity, 65.1%; specificity, 85.7%; area under the curve [AUC], 0.76) and 2.4 for ER angular velocity (sensitivity, 80.0%; specificity, 50.0%; AUC, 0.74). CONCLUSION: Greater preoperative instability was a risk factor for residual instability as measured intraoperatively by a quantitatively evaluation in the pivot shift during ACL reconstruction. Quantitative measurements of instability during the pivot shift mechanism under general anesthesia may enable surgeons to predict postoperative residual instability.

Anterolateral ligament reconstruction as an augmented procedure for double-bundle anterior cruciate ligament reconstruction restores rotational stability: Quantitative evaluation of the pivot shift test using an inertial sensor.

PURPOSE: The purpose of this study was to investigate the biomechanical function of the anterolateral structures (ALS) of the knee regarding rotational stability, and to attempt to verify the effectiveness of anterolateral ligament (ALL) reconstruction concomitant with double-bundle anterior cruciate ligament (ACL) reconstruction by quantifying the pivot shift test (PST) using an inertial sensor. METHODS: Six knees of the fresh-frozen cadavers were evaluated during the following phases: (1) [Intact]; (2) ACL-deficient [ACL-D]; (3) ACL-reconstructed [ACL-R]; (4) ACL-reconstructed + ALS-deficient [ACL-R + ALS-D]; and (5) combined ACL and ALL reconstructed [ACL-R + ALL-R]. We evaluated knee rotational instability during each phase using the PST. We used an inertial sensor to calculate tibial external rotational angular velocity (ERAV) and tibial acceleration. Data were analyzed using repeated-measures analysis of variance; statistical significance was accepted as P < 0.05. RESULTS: Relative to [Intact], [ACL-D] caused a significant increase in ERAV and acceleration. However, there was no difference in these parameters between [ACL-R] and [Intact]. [ACL-R + ALS-D] increased ERAV significantly compared with [ACL-R], and there was a significant difference between ERAV during [ACL-R + ALS-D] and [Intact]. However, ERAV was significantly reduced during [ACL-R + ALL-R] compared with [ACL-R + ALS-D], and there was no significant difference in ERAV or acceleration between [ACL-R + ALL-R] and [Intact]. CONCLUSIONS: ALS controlled rotational instability in cooperation with the ACL in a cadaveric model. In cases of combined injury of ACL and ALS, concomitant ACL and ALL reconstruction may restore knee stability comparable with the intact state.