Difference of preoperative varus-valgus stress radiograph is effective for the correction accuracy in the preoperative planning during open-wedge high tibial osteotomy.

PURPOSE: This study aimed to evaluate (1) the efficacy of varus-valgus stress radiographs to adjust the preoperative soft-tissue imbalance and (2) ascertain whether varus-valgus stress radiographs are effective for the correction accuracy in the preoperative planning of the opening wedge high tibial osteotomy (OWHTO). METHODS: From February 2017 to December 2018, a total of 121 consecutive knees that underwent bi-planar OWHTO were enrolled in this retrospective analysis. Preoperative planning was performed using a weight-bearing line (WBL). Target WBL was determined according to the status of the medial compartments such as cartilage, meniscus, and preoperative arthritic grade. Preoperative varus-valgus stress radiographs were used to assess the preoperative mediolateral ligament imbalance. The final target correction length of the opening gap was determined by subtracting the difference between the varus-valgus stress radiographs (VVD). All patients were divided into two groups according to the preoperatively planned correction degree: (group A), smaller than average; (group B), larger than average. Patients were also divided into two other groups (VVD adjusted and neglected groups). RESULTS: Groups A and B were 56 and 54 knees, respectively. The preoperatively planned correction lengths of the opening gap were 9.33 ± 1.5 and 14.16 ± 3.96 mm, respectively (p < 0.01). Mean values of the VVD were 0.85 ± 0.72, and 1.27 ± 1.78 mm, respectively (p < 0.01). Correction errors were 2.17 ± 2.06 and 3.52 ± 2.16%, respectively (p < 0.01). Planned and final correction degrees were also significantly larger (p < 0.01, and p < 0.01, respectively), because the preoperative WBL ratio was significantly smaller in the VVD adjusted group (p < 0.01). CONCLUSION: The VVD values could reproduce the preoperative soft-tissue imbalance and it was more prominent as the correction degree increased. The strategy of subtracting the VVD as assumed soft-tissue imbalance in the preoperative planning worked well for the correction accuracy during OWHTO. LEVEL OF EVIDENCE: Level IV, retrospective study.

Pitfalls in assessing limb alignment affected by rotation and flexion of the knee after total knee arthroplasty: Analysis using sagittal and coronal whole-body EOS radiography.

BACKGROUND: Inappropriate posture during radiographic assessment may lead to misunderstanding of postoperative alignment after total knee arthroplasty (TKA). The EOS system assesses coronal and sagittal alignment simultaneously. This study aimed to evaluate the effect of flexion and/or rotation on alignment, and identify the patterns of knee posture with serial follow-up using the EOS system. METHODS: One-hundred and fifteen patients of TKA and serial whole-body EOS were included. The hip-knee-ankle (HKA) angle in the coronal and sagittal planes, femoral component rotation ratio (FCR), tibial component rotation ratio (TCR), and fibular overlap ratio (FO) were measured immediately and at six months and one year postoperatively. Total and partial correlation, using flexion and rotation as a control variable was performed. RESULTS: The mean HKA values and flexion immediately post-operation were different compared with the values noted at six months and one year postoperatively (for all, P < 0.05). The FCR and FO were correlated with the HKA angle during all periods (for both, P < 0.05). The Pearson correlation coefficients of the HKA angle with rotation parameters decreased when flexion was controlled. CONCLUSIONS: Combined rotation and flexion of the knee joint has a greater effect on coronal alignment compared with isolated flexion or rotation and was more frequently observed during the early postoperative period. Therefore, surgeons should be made aware of the potential knee rotation and flexion errors after TKA.

How does geometric change after open-wedge high tibial osteotomy affect anterior cruciate ligament status?

BACKGROUND: Open-wedge high tibial osteotomy (OWHTO) produces three- dimensional (3D) geometric changes. Among them, increased posterior tibial slope (PTS), and altered coronal inclination that induces unintended tibial translation may affect anterior cruciate ligament (ACL) status. The purpose of current study was to evaluate the geometric changes following OWHTO, such as increasing PTS and decreasing tibial subluxation, which may affect the status of ACL. METHODS: From April 2014 to December 2015, a total of 72 knees in 64 patients that underwent OWHTO, second-look arthroscopy, and magnetic resonance imaging (MRI) assessment, were enrolled. Preoperative and postoperative coronal and sagittal translation, joint line orientation angle, the distance between medial femoral notch marginal line and medial tibial spine, and PTS were evaluated. ACL status was arthroscopically graded from grade 1 (best) to 4 (worst). The MRI signal of the graft in three portions (proximal, middle, and distal) was graded from grade 1 (best) to 4 (worst). RESULTS: High grade (3: partial, and 4: complete rupture) was noted in 28 cases (38.9%) at the second-look arthroscopy compared with 10 cases (13.9%) at index arthroscopy. The MRI signal grade significantly increased at follow up MRI compared with preoperative MRI (P<0.01). An increased signal was commonly noted in the middle and distal portions of the graft. CONCLUSIONS: Geometric changes after OWHTO were related to ACL deterioration. The ACL was commonly affected at the middle and distal portions and rarely at the proximal portion. There is a possibility of impingement because of the geometric changes. LEVEL OF EVIDENCE: Level IV.

Morphometric Assessment of Resected Femoral Cut Surface in Korean Knees and Its Fitting With Western-Designed Femoral Components.

BACKGROUND: This study aimed at assessing the morphometry of resected femurs in Korean patients during total knee arthroplasty (TKA) and comparing these measurements with current Western-designed femoral component dimensions. METHODS: This single-blind, prospective, randomized, controlled trial involved intraoperative measurements for 271 femoral component implantations from 3 contemporary TKA systems, with 2 systems offering narrow sizing options. The difference between femoral component dimensions and the resected surface of distal femur was measured in millimeters at 5 distinct zones. RESULTS: Overhang of standard femoral component was common in the anterior-medial condyle and anterior-lateral condyle ranging from 50.8% to 99.0% and 21.5% to 88.0%, respectively. With narrow femoral components, the rate of overhang reduced to 21.5%-30.2% and 9.2%-32.1%. Conversely, underhang rates were higher over the anterior flange width, middle medial-lateral and posterior medial-lateral zones. Standard components displayed higher underhang rates at these zones compared to narrow components. The good fit rate for femoral component was low among the 3 systems ranging from 1.0% to 56.0%. System with narrow option sizing increases the underhang rates in males, while improving the component fit among females at similar zones with rate ranging from 5.2% to 52.9%. CONCLUSION: Currently available TKA implant designs may not provide a perfect match for the distal femoral shape of the Korean population. The availability of implants with standard and narrow options can substantially improve the optimal fitting of femoral components in the Korean population.

Enhanced Tendon-to-Bone Healing of Chronic Rotator Cuff Tears by Bone Marrow Aspirate Concentrate in a Rabbit Model.

BACKGROUND: To evaluate the influence of bone marrow aspirate concentrate (BMAC) on tendon-to-bone healing in a rabbit rotator cuff model and to characterize the composition of growth factors in BMAC. METHODS: In this in vivo study, 40 rabbits were allocated into five groups: control (C), repair + saline (RS), repair + platelet-rich plasma (PRP; RP), repair + BMAC (RB) and repair + PRP + BMAC (RPB). A tear model was created by supraspinatus tendon transection at the footprint. Six weeks after transection, the torn tendon was repaired along with BMAC or PRP administration. Six weeks after repair, shoulder samples were harvested for biomechanical and histological testing. Ten rabbits were used for processing PRP and BMAC, followed by analysis of blood cell composition and the levels of growth factors in vitro. RESULTS: The ultimate load-to-failure was significantly higher in RPB group compared to RS group (p = 0.025). BMAC-treated groups showed higher values of biomechanical properties than RS group. The histology of BMAC-treated samples showed better collagen fiber continuity and orientation than RS group. BMAC contained significantly higher levels of the several growth factors than PRP. CONCLUSIONS: Locally administered BMAC enhanced tendon-to-bone healing and has potential for clinical applications.