CT-Based Calculation Model Assists Precise Treatment for Anterior and Posterior Ankle Bony Impingement.

OBJECTIVE: Ankle arthroscope is the preferred tool for ankle surgeons to treat ankle impingement. However, there is no relevant report on how to improve the accuracy of arthroscopic osteotomy through preoperative planning. The aims of this study were to investigate a novel method to obtain the bone morphology in anterior and posterior ankle bony impingement through computed tomography (CT) calculation model, use this method to guide surgical decision-making, and compare the postoperative efficacy and actual bone cutting volume with conventional surgery. METHODS: This retrospective cohort study includes 32 consecutive cases with anterior and posterior ankle bony impingement by arthroscopy from January 2017 to December 2019. Mimics software was utilized to calculate the bony morphology and measure the volume of the osteophytes by two trained software engineers. The patients were divided into the precise group (n = 15) and the conventional group (n = 17) according to whether obtain and quantify the osteophytes' morphology with CT based calculation model preoperative. All patients were evaluated clinically using visual analog scale (VAS) score, American Orthopaedic Foot and Ankle Society (AOFAS) score, active dorsiflexion and plantarflexion angle before and after surgery at both 3 months and 12 months postoperatively. We obtained the shape and volume of bone cutting through Boolean calculation. Clinical outcomes and radiological data were compared between the two groups. RESULTS: The VAS score, AOFAS score, active dorsiflexion angle and plantarflexion angle were significantly improved in both groups postoperatively. In comparison of the VAS score, AOFAS score, and active dorsiflexion angle, the precise group were higher than the conventional group in the follow-up at 3 and 12 months postoperatively with statistical difference. The difference between the virtual bone cutting volume and the actual bone cutting volume of the anterior edge of distal tibia in the conventional group and precise group were 244.20 ± 147.66 mm3 and 76.53 ± 168.51 mm3 , respectively, there was statistical difference between the two groups (t = -2.927, p = 0.011). CONCLUSION: Using a novel method of obtaining and quantifying the bony morphology with CT-based calculation model for anterior and posterior ankle bony impingement can help guide surgical decision-making preoperatively and assist precise bone cutting during the operation, which can improve the efficacy and evaluate the accuracy of osteotomy postoperatively.

Optimal Sagittal Insertion Depth and Direction of Femoral Intramedullary Rod in Total Knee Arthroplasty in Chinese Osteoarthritis Patients.

OBJECTIVE: To identify the optimal femoral intramedullary rod insertion depth and direction on the sagittal plane in total knee arthroplasty (TKA) of Chinese osteoarthritis (OA) patients. METHODS: From January to December 2019, CT data were collected for 85 consecutive entire lower extremity Chinese OA patients. A three-dimensional method was used to simulate intramedullary rod penetration. The intramedullary rods were inserted toward the anterior (TA), center (TC), and posterior (TP) of the femoral canal, respectively. Four penetration depths of 150, 200, 250, and 300 mm from the joint line were set. The intersection angle was measured between the simulated intramedullary rod and the mechanical axis of the femur (FMA) on the sagittal plane. RESULTS: Our study included 85 Chinese OA patients: 46 women, with a mean age of 65.7 ± 8.4 years (range, 51-85 years) and 39 men, with a mean age of 65.6 ± 8.1 years (range, 46-86 years). The intersection angle between the FMA and the femoral anatomical axis was smaller in men, 2.4° ± 1.6° (range, 0°-4.8°), than in women, 3.5° ± 2.3° (range, 0.7º-8.2°), with a significant statistical difference (P < 0.01). In the comparison of the intersection angle between the simulated intramedullary rod and the FMA, there was no statistical difference between TA200 and TC200 in women (P > 0.05). The proportions were up to 91% and 96% of TA200 at 0°-3° and 0°-5° intervals, respectively, but just 63% and 78% in TC200. In TA150, 76% of intersection angles were greater than 5°. Only approximately 60% in TA250 and TA300 were within the 0°-5° interval and 40% were less than 0°. Only 57% of intersection angles in TC150 were in the 0°-3° interval. TC250, TC300, and TP150 were mostly below 0°. In men, there were statistical differences between all groups. All intersection angles were greater than 5° in TA150. TA200 and TA250 were mostly greater than 5° (87% and 59%, respectively) and 72% of intersection angles were within 0°-5° interval in TA300. TC150 had 92% of intersection angles within the 0°-5° interval but only 62% between the 0° and 3° interval. In the TC200, up to 90% and 97% were within 0°-3° and 0°-5° intervals, respectively. TC300, TP150, and TP200 were mostly below 0°. CONCLUSION: We described an innovative method for rapidly, simply, and accurately identifying the sagittal insertion depth and direction of the femoral intramedullary rod in TKA, which can optimize the position of the femoral prosthetic component on the sagittal plane in TKA.

Biomechanics of single-tunnel double-bundle anterior cruciate ligament reconstruction using fixation with a unique expandable interference screw.

BACKGROUND: Single-tunnel double-bundle (STDB) anterior cruciate ligament (ACL) reconstruction can restore biomechanical function and anatomic structure, but existing methods of graft fixation are not adequate. The aims of this study are to examine knee biomechanics after STDB reconstruction using a unique expandable interference screw for fixation. METHODS: The biomechanical parameters of six pairs of human cadaveric knee specimens were measured with the ACL intact, after ACL removal, and after STDB reconstruction using the interference screw or single-tunnel single-bundle (STSB) reconstruction. Anterior tibial translation under 134 N anterior tibial load in a neutral position as well as in 15° and 30° internal and external knee rotation and the internal tibial rotation angle under the rotatory load (5 N·m internal tibial rotation) were measured. RESULTS: Anterior tibial translations at each degree of knee flexion in the STDB group were significantly less than in the STSB group (all, P<0.05). The internal rotation angles in the STSB group at five flexion angles were significantly higher than in the ACL intact group, whereas there were significantly less than those of the ACL absent group (P<0.05). Under rotatory loads in the neutral position, the tibial internal rotation angles of the STDB group were significantly lower than in the STSB group at all flexion angles (all, P<0.05). CONCLUSIONS: STDB ACL reconstruction with the expandable interference screw provides better anteroposterior and rotational stability than STSB reconstruction. CLINICAL RELEVANCE: The technique provides the advantages of double-bundle reconstruction using a single-tunnel technique.