Fibular morphology is not associated with incidence of peroneal tendon dislocation.

PURPOSE: The association of peroneal tendon dislocation with peroneal bone morphology and postoperative redislocation rates remains unknown. This study compared the fibula morphology in patients with peroneal tendon dislocation with that in a control population. METHODS: The study enrolled 48 patients who underwent surgery for peroneal tendon dislocation at our institution during between 2018 and 2023. Thirty-five patients with preoperative magnetic resonance imaging of the ankle were defined as Group D and 35 with magnetic resonance imaging of the ankle for other reasons and with similar background data were selected as the control group (Group C). The posterior tilting angle of the fibula, posterolateral angle and posterolateral edge angle were evaluated at the plafond level. The posterior tilting angle, posterolateral angle and retromalleolar bone shape according to the Rosenberg classification (flat, convex, concave) were evaluated at the midpoint between the plafond and the tip. RESULTS: At the plafond level, the posterior tilting, posterolateral and posterolateral edge angles were 57.7 ± 11.1°, 123.8 ± 12.3° and 90.8 ± 13.7°, respectively, in Group D and 64.1 ± 15.4°, 121.1 ± 12.3° and 88.7 ± 12.2°, respectively, in Group C, with no significant differences. No significant between-group differences existed in the posterior tilting and posterolateral angles at the midpoint level. Moreover, no significant differences existed in distribution of the bone geometry according to the Rosenberg classification. CONCLUSION: There were no differences in morphology between patients with peroneal tendon dislocation and controls. This study provides useful information on the indications for primary surgery and whether bony approach is useful for peroneal tendon dislocation. LEVEL OF EVIDENCE: Level IV.

Risk factors for anteroposterior laxity increase over time in double-bundle anterior cruciate ligament reconstruction using hamstring autografts.

PURPOSE: An anteroposterior (AP) laxity can increase over time after anterior cruciate ligament reconstruction (ACLR) using hamstring tendons; however, the associated risk factors remain unclear. This study aimed to investigate the risk factors of this phenomenon. METHODS: Overall, 151 patients who underwent ACLR using hamstring autografts were recruited. AP laxity was evaluated using Knee Lax 3 arthrometer at 5 months, 1 and 2 years postsurgery. Patients were categorised into groups I (>1 mm increase) and C (<1 mm increase) based on whether they experienced an irreversible increase in AP laxity after 1 or 2 years compared with 5 months. Patient demographics and Knee injury and Osteoarthritis Outcome Score (KOOS) at 2 years postsurgery were compared between groups. RESULTS: Group I (n = 33, 21%) showed a side-to-side difference of 4.6 (3.0-7.2) mm in AP laxity preoperatively and 0.3 (-0.7 to 1.3), 1.1 (0.2-1.9) and 2.4 (1.7-3.2) mm at 5 months, 1 and 2 years postoperatively, while group C (n = 119, 79%) showed 4.3 (2.8-5.7) mm preoperatively and 1.3 (0-1.9), 0.9 (0.1-1.8) and 0.6 (-0.3 to 1.5) mm, respectively. No significant differences were observed in the overall KOOS at 2 years (n.s.). However, group I was older (36 [22-46] vs. 28 [19-39] years; p = 0.044), had longer surgical waiting periods (122 [69-341] vs. 81 [52-136] days; p = 0.041) and lower preoperative Tegner activity scale scores (6 [5-7] vs. 7 [6,7]; p = 0.002). CONCLUSION: While 33 patients (21%) experienced AP laxity increase over time, they had comparable clinical outcomes with group C. LEVEL OF EVIDENCE: Level III.

Risk factors for hamstring strain injury in male college American football players -a preliminary prospective cohort study.

BACKGROUND: Given the frequency of hamstring strain injuries (HSI) among male college American football players, several studies have attempted to determine whether certain risk factors can predict their occurrence. However, no consensus on modifiable risk factors for HSIs in male college American football players has yet been reached to prevent these injuries. This study aimed to clarify risk factors for HSI prospectively in college male American football players. METHODS: A total of 78 male college American football players, whose positions were limited to skill positions, were medically assessed for potential risk factors of HSI. The preseason medical assessment included anthropometric measurements, joint laxity and flexibility, muscle flexibility, muscle strength, and balance ability. RESULTS: HSI occurred in a total of 25 thighs from 25 players (32.1%). Injured players had significantly lower hamstring flexibility (p = 0.02) and hamstring to quadriceps strength ratio (H/Q) (p = 0.047) compared to uninjured players. Additionally, injured players had significantly lower general joint laxity scores, especially for the total (p = 0.04), hip (p = 0.007), and elbow (p = 0.04) scores, compared to uninjured players. CONCLUSIONS: Lower hamstring flexibility, lower hamstring to quadriceps strength ratio, and lower general joint laxity score were identified as risk factors for HSI in male college American football players placed in skill positions. The muscle flexibility and H/Q ratio could be useful in preventing HSI in such players.

Effects of a 1-mm difference in bearing thickness on intraoperative bearing movement and kinematics in Oxford unicompartmental knee arthroplasty.

BACKGROUND: The choice of mobile bearing (MB) thickness is essential for obtaining successful results after mobile-bearing Oxford unicompartmental knee arthroplasty (UKA). This study aimed to investigate the effects of a 1-mm difference in bearing thickness on intraoperative MB movement and intraoperative knee kinematics in Oxford UKAs. METHODS: We prospectively investigated the effects of a 1-mm difference in bearing thickness on intraoperative MB movement and knee kinematics in 25 patients who underwent Oxford UKAs when surgeons didn't know which bearing thickness to choose with 1-mm difference. A trial tibial component that was scaled every 2 mm was used to measure the intraoperative MB movement, and the tibial internal rotation relative to the femur and the knee varus angle was simultaneously evaluated using the navigation system as the knee kinematics. We separately evaluated sets of two MB thicknesses with 1-mm differences, and we compared the intraoperative parameters at maximum extension; 30º, 45º, 60º, and 90º flexion; and maximum flexion between the thicker MB (thick group) and the thinner MB (thin group). RESULTS: The MB in the thin group was located significantly posteriorly at 90º flexion compared with that in the thick group; however, there were no differences at the other flexion angles. There was significantly less tibial internal rotation in the thin group at 90º flexion than that in the thick group; however, there were no differences at the other flexion angles. The knee varus angles in the thick group were significantly smaller than those in the thin group by approximately one degree at all angles other than at 30º and 45º flexion. CONCLUSION: The thicker MB could bring the less posterior MB movement and the more tibial internal rotation at 90º flexion, additionally the valgus correction angle in the thicker MB should be paid attention. These results could help surgeons to decide the thickness of MBs when they wonder the thickness of MB.

Intraoperative rotational kinematics and its influence on postoperative clinical outcomes differ according to age in Unicompartmental knee Arthroplasty.

BACKGROUND: Although Oxford unicompartmental knee arthroplasty (UKA) is used in patients of wide age ranges, there is no clear information regarding the age differences in terms of intraoperative femorotibial rotational kinematics and its influence on clinical outcomes. Therefore, this study was conducted to examine the age differences in terms of intraoperative rotational kinematics and postoperative clinical outcomes and to analyze their relationship with classification according to the age group. METHODS: We investigated 111 knees of patients who underwent Oxford UKA using a navigation system and divided them into two groups: elderly (aged ≥75 years; 48 knees) and nonelderly (aged < 75 years; 63 knees). Intraoperative tibial internal rotational angles relative to the femur during passive knee flexion were measured using a navigation system, and clinical outcomes were evaluated using knee range of motion, the Knee Injury and Osteoarthritis Outcome Score (KOOS), and the Knee Society Functional Score at 2 years postoperatively. The relationships between intraoperative tibiofemoral rotational angles and clinical outcomes were also evaluated in the two groups. RESULTS: The intraoperative tibial internal rotational angle relative to the femur during knee flexion was significantly larger in the nonelderly group (13.5°) than in the elderly group (9.0°). The intraoperative tibial internal rotational angle showed a positive correlation with the pain subscale of KOOS only in the nonelderly group. CONCLUSION: Intraoperative rotational kinematics and its influence on clinical outcomes were different between elderly and nonelderly patients, and the tibial internal rotational angle could be a more important factor for successful UKA in nonelderly patients.

Both intraoperative medial and lateral soft tissue balances influence intraoperative rotational knee kinematics in bi-cruciate stabilized total knee arthroplasty: A retrospective investigation.

BACKGROUND: Tibial internal rotation following total knee arthroplasty (TKA) is important in achieving favorable postoperative clinical outcomes. Studies have reported the effect of intraoperative soft tissue balance on tibial internal rotation in conventional TKA, no studies have evaluated the effects of soft tissue balance at medial or lateral compartments separately on tibial internal rotation in bi-cruciate stabilized (BCS) TKA. The purpose of this study was to clarify the relationship between medial or lateral component gaps and rotational knee kinematics in BCS TKA. METHODS: One hundred fifty-eight knees that underwent BCS TKA were included in this study. The intraoperative medial and lateral joint laxities which was defined as the value of component gap minus the thickness of the tibial component were firstly divided into two groups, respectively: Group M-stable (medial joint laxity, ≤ 2 mm) or Group M-loose (medial joint laxity, ≥ 3 mm) and Group L-stable (lateral joint laxity, ≤ 3 mm) or Group L-loose (lateral joint laxity, ≥ 4 mm). And finally, the knees enrolled in this study were divided into four groups based on the combination of Group M and Group L: Group A (M-stable and L-stable), Group B (M-stable and L-loose), Group C (M-loose and L-stable), and Group D (M-loose and L-loose). The intraoperative rotational knee kinematics were compared between the four Groups at 0°, 30°, 60°, and 90° flexion, respectively. RESULTS: The rotational angular difference between 0° flexion and maximum flexion in Group B at 30° flexion was significantly larger than that in Group A at 30° flexion (*p < 0.05). The rotational angular difference between 30° flexion and maximum flexion in Group B at 30° flexion was significantly larger than that in Group D at 30° flexion (*p < 0.05). The rotational angular differences between 30° or 90° flexion and maximum flexion in Group B at 60° flexion were significantly larger than those in Group A at 60° flexion (*p < 0.05). CONCLUSION: Surgeons should pay attention to the importance of medial joint stability at midflexion and lateral joint laxities at midflexion and 90° flexion on a good tibial internal rotation in BCS TKA.

Weight-bearing knee flexion angle better correlates with patient-reported outcome measures than non-weight-bearing condition in total knee arthroplasty: a three-dimensional analysis study.

BACKGROUND: This study aims to elucidate and compare the relationship between the knee flexion angle and patient-reported outcome measures (PROM) in both non-weight-bearing (NWB) and weight-bearing (WB) conditions. METHODS: This retrospective cohort study included 61 knees (47 patients) who underwent total knee arthroplasty. The knee flexion angle was measured by three conditions: NWB in manual goniometer, NWB in fluoroscopic three-dimensional (3D) analysis and WB in the fluoroscopic 3D analysis. The PROM was evaluated by postoperative 2011 Knee Society Score (2011 KSS) and Knee injury and Osteoarthritis Outcome Score (KOOS). Correlations between the knee flexion angle and PROM was analyzed using Spearman's correlation coefficient. Additionally, whether the angular difference between NWB and WB correlated with the PROM or not was evaluated. RESULTS: The NWB knee flexion angle in a goniometer, NWB in 3D analysis, and WB in 3D analysis were 124.6° ± 8.4°, 118.0° ± 10.5°, and 109.5° ± 13.3°, respectively. The angular difference was 8.5° ± 12.8°. No PROM correlation existed in NWB using a goniometer. Moreover, significant positive correlations in 2011 KSS symptoms (r = 0.35) and 2011 KSS functional activities (r = 0.27) were noted in NWB using 3D analysis. Significant positive correlations existed in 2011 KSS symptoms (r = 0.32), 2011 KSS functional activities (r = 0.57), KOOS pain (r = 0.37), KOOS activity of daily living (ADL; r = 0.45), KOOS sports (r = 0.42), and KOOS quality of life (r = 0.36) in WB using 3D analysis. Significant negative correlations were noted in 2011 KSS functional activities (r = - 0.45), KOOS ADL (r = - 0.30), and KOOS sports (r = - 0.38) in angular difference. CONCLUSIONS: The WB knee flexion angle better correlated with PROM compared with NWB by evaluation of 3D analysis. The larger the angular difference existed between NWB and WB, the lower the PROM score.

Circumferential Cross-Stitch Suture for Longitudinal Lateral Meniscal Tear Around the Popliteal Tendon Hiatus Region.

Lateral meniscal repair of the popliteal hiatus is technically demanding. The inside-out technique requires an additional incision and carries the risk of posterolateral soft tissue damage to the knee joint. In addition, the presence of the popliteal tendon limits the route of the suture thread. Within the current trend of the all-inside suture technique, meniscal suture-based all-inside repair demonstrates biomechanical advantages over anchor-based all-inside repair. We introduce a meniscal suture-based all-inside meniscal repair technique for longitudinal lateral meniscal tears.

Both Intraoperative Medial and Lateral Joint Stabilities at Midflexion Influence Postoperative Patient-Reported Outcome Measures Following Bi-Cruciate Stabilized Total Knee Arthroplasty.

Bi-cruciate stabilized (BCS) total knee arthroplasty (TKA) was developed to approximate normal knee kinematics and is expected to improve clinical outcomes. However, the effects of soft tissue balance at the medial or lateral compartment on patient-reported outcome measures (PROMs) following BCS TKA are unclear. The purpose of this study was to clarify the relationship between the medial or lateral component gaps and PROMs following BCS TKA. One hundred seventeen knees with varus deformities which underwent BCS TKA were included in this study. They were divided into two groups according to the validated Japanese version of the Knee Injury and Osteoarthritis Outcome Score for each subscale of pain, symptoms, and activities of daily living (ADL) at 1 year postoperatively: group H consisted of patients with ≥90 points and group L consisted of patients with <90 points. Intraoperative medial and lateral joint laxities at 0°, 30°, 60°, 90°, and 120° flexion measured using a tensor device were compared between the two groups in each subscale. In the pain subscale, the medial joint laxities at 30° (p < 0.05) and 60° flexion (p < 0.05) in group H were significantly smaller than those in group L. In the ADL subscale, the medial joint laxity at 60° flexion in group H was significantly smaller than that in group L (p < 0.05). In the symptom subscale, the lateral joint laxity at 60° flexion in group H was significantly smaller than that in group L (p < 0.05). Surgeons should pay attention to the importance of both medial and lateral joint stabilities to achieve better postoperative PROMs following BCS TKA.

Intraoperative femoral rotational kinematics are similar in varus and valgus knees during medial pivot total knee arthroplasty.

BACKGROUND: Medial-pivot type total knee arthroplasty is designed to reproduce physiological femoral rotational kinematics during knee flexion; however, its rotational kinematics in valgus knees remain unknown. This study's hypothesis is that its kinematics show the similar medial pivot motion in valgus knees as in varus knees. METHODS: This retrospective study included 50 cases of primary medial-pivot type total knee arthroplasty performed with navigation for knee osteoarthritis. Cases were grouped as valgus (n = 20) or varus (n = 30). In valgus knees, surgeons used preoperative manual testing to confirm that alignment was correctable. They evaluated femoral rotational kinematics at maximum extension, 30°, 60°, 90°, and maximum flexion, using a navigation system, both before and after implantation. Finally, intraoperative rotational kinematics, postoperative patient-reported outcomes, and knee range of motion were compared between the two groups. FINDINGS: Before implantation, both valgus and varus knees displayed external femoral rotation relative to the tibia during knee flexion. The rotation magnitude was significantly larger in varus knees at 60°, 90°, and maximum flexion angles compared to valgus knees (P < 0.05). In contrast, after implantation, both groups displayed external femoral rotation of 12-13° during knee flexion with no significant differences between the two groups at any knee flexion angle tested (P > 0.05). Short-term clinical outcomes were comparable between valgus and varus knees. INTERPRETATION: Postoperatively, medial-pivot type total knee arthroplasty for knee osteoarthritis resulted in external femoral rotation during knee flexion. Notably, this occurred even in valgus knees with good short-term clinical outcomes.

Anterior cruciate ligament-deficient knee induces a posterior location of the femur in the medial compartment during squatting.

Although an anterior cruciate ligament (ACL) deficiency induces knee osteoarthritis, particularly in the medial compartment, the kinematics remains partially unclear. This study investigated the in vivo knee kinematics of ACL-deficient and normal knees by comparing them during squatting. This prospective comparative study included 17 ACL-deficient knees and 20 normal knees. The kinematics was investigated under fluoroscopy using a two- to three-dimensional registration technique. The anteroposterior (AP) translation of the medial and lateral sides of the femur, axial rotation of the femur relative to the tibia, and kinematic pathways were evaluated and compared. At first, the medial AP position of the femur translated anteriorly from 0° to midflexion, afterward it translated posteriorly in both ACL-deficient and normal knees. However, the medial AP position of the femur in the ACL-deficient knees was located significantly posteriorly compared with normal knees at 0-110° flexion. The lateral AP position of the femur translated posteriorly from 0° to 150° flexion in both ACL-deficient and normal knees. The lateral AP position of the femur in the ACL-deficient knees was located significantly posteriorly compared with that in normal knees at 0-10° flexion. The femur showed external rotation from 0° to 150° flexion in both ACL-deficient and normal knees. A medial pivot motion and subsequent bicondylar rollback were observed in both knees in the kinematic pathway. In conclusion, the AP position of the femur relative to the tibia was altered due to ACL deficiency, particularly in the medial compartment.

Proximal tibial morphology is associated with risk of trauma to the posteromedial structures during tibial bone resection reproducing the anatomical posterior tibial slope in bicruciate-retaining total knee arthroplasty.

BACKGROUND: A tibial cut with the native posterior tibial slope (PTS) is a theoretical prerequisite in bicruciate-retaining total knee arthroplasty (BCRTKA) to regain physiological knee kinematics. The present study reveals tibial morphological risk factors of trauma to the posteromedial structures of the knee during tibial bone resection in BCRTKA. METHODS: Fifty patients undergoing BCRTKA for varus knee osteoarthritis were analyzed. A three-dimensional tibial bone model was reconstructed using a computed tomography-based preoperative planning system, and the coronal tibial slope (CTS) and medial PTS (MPTS) were measured. Then, we set the simulated tibial cutting plane neutral on the coronal plane, posteriorly inclined in accordance with the MPTS on the sagittal plane, and 9 mm below the surface of the subchondral cortical bone (i.e., 11 mm below the surface of the cartilage) of the lateral tibial plateau. The association between the tibial morphology and the distance from the simulated cutting plane to the semimembranosus (SM) insertion (Dsm) was analyzed. RESULTS: Of the 50 patients, 19 (38%) had negative Dsm values, indicating a cut into the SM (namely, below the posterior oblique ligament) insertion. The MPTS was negatively correlated with Dsm (r = -0.396, p = 0.004), whereas the CTS was positively correlated with Dsm (r = 0.619, p < 0.001). On multivariate linear regression analysis, the MPTS and CTS were independent predictors of Dsm. CONCLUSION: In the setting of tibial cuts reproducing the native MPTS in BCRTKA, patients with larger PTS and smaller CTS had more risk of trauma to the posteromedial structures.

The intraoperative gap differences due to joint distraction force differences in total knee arthroplasty are affected by preoperative lower limb alignment and body mass index.

BACKGROUND: Soft tissue balance is important for a good clinical result in total knee arthroplasty. Nevertheless, the appropriate evaluation of the intraoperative gap has not been established. We investigated the relationship between physical characteristics and gap differences due to distraction force, in order to determine whether intraoperative adjustment of the distraction force can be considered based on the physical characteristics of the patient. METHODS: A total of 115 varus knees in which primary total knee arthroplasty was performed were retrospectively evaluated. The component gaps were measured under 60 and 80 N. The gap difference under 60 and 80 N was calculated. We performed a linear regression analysis to determine the correlation between the gap differences and patient parameters. FINDINGS: Each gap was significantly larger under 80 N than under 60 N. The component gap difference is larger in the lateral compartment than in the medial compartment at each knee flexion angle. The gap difference negatively correlated with preoperative hip-knee-ankle angle at a knee flexion of 0° and 120° (r = -0.21, -0.19; p = 0.02, 0.05) and positively correlated with BMI in the lateral compartment at a knee flexion of 90° (r = 0.31, p < 0.001). INTERPRETATION: The difference in the intraoperative gap due to the joint distraction force was affected by the preoperative HKA axis angle and the body mass index in the lateral compartment. Surgeons should consider the effect of preoperative limb alignment and body mass index in interpreting intraoperative gap measurement.

The effects of initial graft tension on femorotibial relationship following anatomical rectangular tunnel anterior cruciate ligament reconstruction using bone-patellar tendon-bone graft.

BACKGROUND: The purpose of this study was to elucidate the effects of the difference of initial graft tension on the femorotibial relationship on an axial plane and its chronological change following anatomical anterior cruciate ligament (ACL) reconstruction. METHODS: A total of 63 patients who underwent anatomical ACL reconstruction were included in this study. The graft was fixed at full knee extension with manual maximum (higher graft tension; group H) and 80 N (lower graft tension; group L) pulls in 31 and 32 patients, respectively. The femorotibial positional relationship in axial computed tomography at 1 week and 1 year postoperatively were retrospectively evaluated. The side-to-side differences (SSDs) and the amount of changes of SSDs over 1 year were compared between groups. RESULTS: The SSDs of the external rotational angle of the tibia in group H were significantly larger than those in group L at postoperative 1 week (2.7 ± 3.9° vs. 0.3 ± 3.3°; P < 0.01). The amount of internal rotational changes of SSDs of the internal-external rotational angles over 1 year in group H was significantly larger than that in group L (-3.6 ± 3.9° vs. - 0.3 ± 2.7°; P < 0.01). No significant differences were observed on the anterior-posterior translation distance and medial-lateral shift distance. CONCLUSION: The application of higher initial graft tension resulted in excessive external rotation of the tibia to the femur at 1 week postoperatively in anatomical ACL reconstruction, and the excessive early external tibial rotation had resolved over 1 year.

The Association between In Vivo Knee Kinematics and Patient-Reported Outcomes during Squatting in Bicruciate-Stabilized Total Knee Arthroplasty.

Bicruciate-stabilized total knee arthroplasty (BCS TKA) has been developed to improve TKA kinematic performance. However, the relationship between in vivo kinematics and patient-reported outcomes (PROs) has not been well described. This study was performed to clarify the relationship between in vivo kinematics and PROs in a cohort of patients undergoing BCS TKA. Forty knees were evaluated using a two-dimensional to three-dimensional registration technique obtained from sagittal plane fluoroscopy. In vivo kinematics including anteroposterior (AP) translation and tibiofemoral rotation were evaluated. Knee Society scores (KSSs) and Knee injury and Osteoarthritis Outcome Scores (KOOSs) were assessed before and after surgery. Relationships between tibiofemoral kinematics assessed with the knee in different positions of knee flexion and PROs were evaluated using Spearman's correlation analysis. The study demonstrated a significant negative correlation (r = - 0.33) between medial AP translation from minimum flexion to 30 degrees flexion and postoperative KOOS activities of daily living subscale. A significant positive correlation (r = 0.51) was found between the femoral external rotation from minimum flexion to 30 degrees flexion and improvement of the KOOS pain subscale. No correlation was found between the lateral AP translation and PROs. Achieving medial AP and femoral external rotation stability in early flexion may be important in optimizing postoperative PROs.

Lateral posterior tibial slope does not affect femoral but does affect tibial tunnel widening following anatomic anterior cruciate ligament reconstruction using a Bone-Patellar Tendon-Bone graft.

Background: Tunnel widening (TW) after anterior cruciate ligament (ACL) reconstruction has been a research area of interest in ACL reconstruction. In recent years, it has been noted that posterior tibial slope (PTS) affects several types of outcomes after ACL reconstruction including TW. However, the relationships between femoral and tibial TW and between PTS and TW following anatomical ACL reconstruction using a bone-patellar tendon-bone (BTB) graft are often not understood. Therefore, the purpose of this study was to retrospectively clarify the magnitude of femoral and tibial TW and the effect of PTS on TW following anatomical ACL reconstruction using a BTB graft. Methods: A total of 111 patients who underwent isolated ACL reconstructions using BTB grafts were included in this study. Femoral and tibial tunnel aperture areas were measured using three-dimensional computed tomography (3D CT) at 1 week and 1 year postoperatively, and femoral and tibial TW (%) was calculated. Lateral and medial PTS was also measured using 3D CT. Results: As compared with 1 week postoperatively, the mean tibial tunnel aperture areas increased by 30.6% ± 28.5%, and the mean femoral tunnel aperture areas increased by 28.3% ± 27.9% when measured at 1 year postoperatively. Although no significant difference was observed between femoral and tibial TW, a significant positive correlation was noted between femoral and tibial TW (r = 0.240, p = 0.011). A significant correlation was observed only between lateral PTS and tibial TW (r = 0.354, p < 0.001). There was no significant correlation between medial PTS and tibial TW, lateral PTS and femoral TW, or medial PTS and femoral TW. Conclusion: Significant positive correlation was observed between femoral and tibial TW. Steeper lateral PTS correlated with greater tibial TW; on the other hand, medial PTS did not correlate with tibial TW. Although lateral PTS affected tibial TW, it did not affect femoral TW.

Comparison of the joint laxity of total knee arthroplasty evaluated by the distraction force and the varus-valgus force.

BACKGROUND: Component gap (CG) measurement help surgeons evaluate intraoperative soft-tissue balance. One technique is measuring the CG using tensioner devices with distraction force. Another is to evaluate the laxity under a varus-valgus force using navigation or robotics. The aim was to compare the JL evaluated by CG and varus-valgus force between the different types of total knee arthroplasties. METHODS: Forty-three bi-cruciate stabilized (BCS) knees and 33 bi-cruciate retaining (BCR) knees were included. After bone resection and soft tissue balancing, the CG was measured and after the final implantation and capsule closure, JL under a maximum varus-valgus stress was recorded with navigation. JL evaluated by the CG (JLCG) was defined as CG minus selected thickness of the tibial component and JL under varus-valgus force (JLVV) was defined as difference between varus-valgus angles without stress and maximum varus-valgus angles under varus-valgus force. The evaluations were performed at flexions of 10°, 30°, 60° and 90°. RESULTS: Although JLCGs of lateral compartment of BCS were larger than those of BCR, no difference was found between JLVVs of BCS and BCR. Although JLCGs of lateral compartment did not change at each knee flexion angle in both BCS and BCR, JLVVs of lateral compartment increased by 3° from 10° to 90° knee flexion. CONCLUSION: JLVVs of BCS and BCR were equivalent, whereas BCS showed larger JLCGs of lateral compartment. JLVVs of lateral compartment increased by 3° in the range from 10° to 90° knee flexion whereas JLCGs remained stable.

Rotational kinematics differ between mild and severe valgus knees in total knee arthroplasty.

BACKGROUND: There is no consensus regarding femorotibial rotational kinematics in total knee arthroplasty (TKA) for valgus knee deformity. Additionally, whether the degree of valgus deformity influences intraoperative rotational kinematics and postoperative clinical scores remains unclear. The objectives of this study were to investigate whether the valgus angle is associated with intraoperative rotational kinematics in TKA for valgus knee deformity and to examine the relationship between rotational kinematics and postoperative clinical results. MATERIALS AND METHODS: A total of 24 knees with valgus deformity for TKA were included in this study and were divided into two groups depending on the femorotibial angle (FTA); there were 11 knees in the severe valgus group (FTA < 160°) and 13 knees in the mild valgus group (FTA ≥ 160°). Intraoperative femorotibial rotational kinematics from knee extension to flexion were evaluated using an image-free navigation system and postoperative clinical results (range of motion and subjective outcomes) were evaluated 1 year postoperatively. All parameters were compared between the two groups. RESULT: Mild valgus knee showed tibial internal rotation during knee flexion before implantation, whereas severe valgus knee showed tibial external rotation during knee flexion before implantation. The postoperative flexion angle was positively correlated with the tibial internal rotation angle after implantation in the mild valgus group only. CONCLUSION: Intraoperative rotational kinematics before implantation differed between mild and severe valgus knee deformity in TKA. Intraoperative tibial rotation influenced the postoperative knee flexion angle in mild, but not severe, valgus knee deformity. Ideal postoperative rotational kinematics may be different between the two groups and the difference may be taken into consideration in implant selections and surgical techniques.

Implant Alignment and Patient Factors Affecting the Short-Term Patient-Reported Clinical Outcomes after Oxford Unicompartmental Knee Arthroplasty.

This study aims at clarifying implant alignment and other patient factors' influence on clinical outcomes, particularly on patient-reported outcomes (PRO), following Oxford unicompartmental knee arthroplasty (OUKA). A total of 142 patients after OUKA were divided into two groups according to the validated Japanese version of the knee injury and osteoarthritis outcome score (KOOS) for each subscale of pain, symptoms, and activities of daily living (ADL) at postoperative year 1 and 2: group 1 had ≥80 scores and group 2 had <80 scores. Postoperative clinical and radiographical findings were then compared among groups in each subscale. Using postoperative year 1 and 2 data, a multivariable logistic regression analysis was conducted to clarify factors for clinical outcomes' improvement. In the analysis of KOOS subscale of symptoms at postoperative year 1, gender distribution, preoperative body mass index, and postoperative maximum knee flexion angles differed significantly among groups. In the analysis for KOOS subscale of ADL, significant differences were observed in postoperative tibial component varus angles. Multivariable logistic regression analysis revealed that all of these parameters significantly related to ≥80 KOOS scores of each subscale at postoperative year 1. Additionally, at postoperative year 2, larger postoperative knee flexion angles and tibial component varus angles related to ≥80 KOOS subscale of symptoms and ADL were observed. In conclusion, tibial component's larger varus alignment was associated with the better PRO at both 1 and 2 years after OUKA. Importantly, larger postoperative knee flexion angle helped achieve good short-term PRO after OUKA.

Hip Abductor Muscle Strength Deficit as a Risk Factor for Inversion Ankle Sprain in Male College Soccer Players: A Prospective Cohort Study.

BACKGROUND: Previous studies have attempted to determine whether certain risk factors can predict the occurrence of inversion ankle sprains in male collegiate soccer players. However, no consensus has been reached on the predictive risk factors of inversion ankle sprain in this population. PURPOSE: To identify risk factors for inversion ankle sprains among male collegiate soccer players. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Included were 145 male collegiate soccer players in Japan who were assessed during a preseason medical checkup for potential risk factors of inversion ankle sprain. The preseason assessment included anthropometric measurements, joint laxity and flexibility, muscle flexibility, muscle strength, and balance ability, with a total of 33 variables. The participants were monitored during the 2019 season for inversion ankle sprains as diagnosed by physicians. RESULTS: A total of 31 inversion ankle sprains in 31 players (21.4%) occurred during the season. Only the measured isometric hip abductor strength was significantly lower in injured players as compared with uninjured players. Logistic regression analysis revealed measured hip abductor muscle strength deficit as a significant risk factor for inversion ankle sprain (odds ratio, 0.978 [95% CI, 0.976-0.999]; P = .05). CONCLUSION: Hip abductor strength deficit was a risk factor for inversion ankle sprain in the study population. This finding could be useful for the prevention of inversion ankle sprains in male collegiate soccer players.