Spacer-based gap balancing is useful in total knee arthroplasty: a 3-year follow-up of a retrospective study

Background Which technique, gap balancing or measured resection, can obtain better femoral component alignment and soft tissue balance in total knee arthroplasty (TKA) is still controversial. This study aimed to determine whether the gap balancing technique using a modified spacer block in TKA can result in better postoperative clinical outcomes than the measured resection technique. Methods A total of 124 patients who underwent consecutive primary TKA between May 2016 and August 2018 were retrospectively reviewed. The gap balancing technique assisted by a modified spacer block was used in 61 patients, and the measured resection technique was used in 63 patients. The surgical, imaging and knee function outcomes of the two groups were compared. Results The thickness of the posterior medial condyle bone resection using the modified spacer block tool in gap balancing was significantly larger than that of the MR technique (P = 0.001). Compared with the measured resection group, the gap balancing group had a greater external rotation resection angle of the femur (4.06 ± 1.10° vs. 3.19 ± 0.59°, P < 0.001°). Despite these differences, the mean ROM, KSS scores, and WOMAC scores at the 6-week, 1-year, and 2-year follow-ups were not significantly different. Postoperatively, there was no significant difference between the two groups in mechanical axis measurements (P = 0.275), the number of HKA outliers (P = 0.795) or the joint line displacement (P = 0.270). Conclusion The functional outcomes of the gap balancing technique based on the modified spacer are similar to those of measured resection at 3 years. Compared with the MR technique, the GB technique resulted in a greater external rotation resection angle and thicker posterior medial condylar cuts in TKA with knee varus.

Knee Stability following Posterior-Stabilized Total Knee Arthroplasty: Comparison of Medial Preserving Gap Technique and Measured Resection Technique

Novel medial preserving gap technique (MPGT) focuses on medial compartment stability and allows lateral physiological laxity. This study aimed to compare the MPGT with the measured resection technique (MRT) to determine which provides better postoperative knee stability after posterior-stabilized total knee arthroplasty (PS-TKA). Primary PS-TKA, using either MPGT (n = 65) or MRT (n = 65), was performed in 130 patients with varus knee osteoarthritis. Postoperative knee stabilities at extension and flexion were assessed using varus–valgus stress radiographs and stress epicondylar view, respectively (at 1 month, 6 months, 1 year, and 3 years postoperatively). The distance between the femoral prosthesis and polyethylene insert was measured on each medial and lateral side, defined as the medial joint opening (MJO) and lateral joint opening (LJO), respectively. Decreasing MJO or LJO translated to increasing postoperative stability. The femoral external rotation angle was compared between the two surgical techniques; postoperative knee stability was also compared between the medial and lateral compartments, as well as the surgical techniques. A significant difference was found in the femoral external rotation angle between MPGT (4.2 ± 0.2 degrees) and MRT (3.6 ± 0.1 degrees, p < 0.01). Postoperative MJOs both at extension and flexion were significantly smaller than LJOs using MPGT and MRT at all time points (p < 0.05). MJOs and LJOs at extension using MPGT were significantly smaller than those when using MRT, at 1 and 3 years postoperatively (p < 0.05). Furthermore, MJOs at flexion using MPGT were significantly smaller than those when using MRT at 6 months, 1 year, and 3 years postoperatively (p < 0.05). MPGT provided higher postoperative medial knee stability than MRT both at extension and flexion, even at 3 years after PS-TKA. This suggests that this newly developed surgical technique is a more feasible option than MRT for the preservation of postoperative medial knee stability.

Patient-specific instrumentation combined with a new tool for gap balancing is useful in total knee replacement: a 3-year follow-up of a retrospective study

Objective The purpose of this study was to determine whether the gap-balancing technique with patient-specific instrumentation (PSI) and a new balancing device in total knee arthroplasty (TKA) can improve knee function to a greater extent than can the measured resection technique. Materials and methods Data from 150 patients who underwent TKA from August 2014 to June 2016 were studied retrospectively. The gap-balancing technique assisted by PSI and the new balancing device was used in 80 patients (82 knees), and the measured resection technique was used in 70 patients (70 knees). The surgical, imaging, and knee function data were compared. Results The gap-balancing technique assisted by PSI and the new balancing device was found to be feasible in all operated knees and reliable. In total, 150 patients (152 knees) of ages ranging from 52 to 78 years (mean 67 years) underwent TKA during the study period. The follow-up period ranged from 35 to 52 months (mean 45 months). Only one patient, who was included in the gap-balancing group, underwent a revision surgery at 2 years postoperatively due to infection. There were no differences in the incidence of anterior knee pain between the two groups. The mean flexion angle, KSS scores, and VAS scores did not significantly differ between the measured resection group and gap-balancing group at 12 weeks or 36 weeks postoperatively. The average joint line displacement was 1.3 ± 1.1 mm (range 0–3) proximally in the GB (gap-balancing) group and 1.2 ± 1.4 mm in the MR (measured-resection) group. No outliers >5 mm in either group were recorded. The mean leg axis deviation from the neutral mechanical axis was 1.8°±1.5° varus (range 0°–3°varus) versus the neutral mechanical axis in the GB group and 1.4°±1.2°(range 0°–3°)in the MR group. No outliers with >3° deviation in either group were recorded. Conclusions The gap-balancing technique performed with the new balancing device and PSI can yield accurate femoral component alignment as well as outcomes similar to those of measured resection at 3 years. The new balancing device can be taken into consideration by surgeons who prefer performing the gap-balancing technique with PSI.

Gap balancing improve squat function and knee function: a randomized controlled trial comparing gap balancing and measured resection

Objective We compared the measured resection (MR) technique and the gap balancing (GB) technique in patients with knee osteoarthritis after primary total knee arthroplasty (TKA) in China to understand the effects of the two techniques on knee function and squat function. Methods From March 2017 to September 2019, a prospective randomized controlled trial was conducted with 96 patients with knee osteoarthritis undergoing primary TKA from March 2017 to September 2019 randomized to GB group (n = 48) and MR group (n = 48). Intraoperative indicators (operation time, osteotomy volume of medial and lateral of posterior femoral condyles, external rotation angle) were recorded during operation. At 1, 3, 6, and 12 months after surgery, all the patients came to the hospital for review and underwent the pain severity, Western Ontario and McMaster University Osteoarthritis Index (WOMAC), knee joint range of motion, Oxford Knee Score (OKS), and American Knee Society Score (AKSS) tests. All patients were followed up for more than 1 year. Results The osteotomy volume of the medial femoral condyle in the GB group was higher than that in the MR group (P<0.05), and the operation time in the GB group was shorter than that in the MR group (P<0.05). At 1, 3, 6, and 12 months after surgery, the pain severity in the GB group was lower than that in the MR group (P<0.05), the knee range of motion in the GB group was larger than that in the MR group (P<0.05), the WOMAC of the GB group was lower than that of the MR group (P<0.05), the OKS of the GB group was higher than that of the MR group (P<0.05), the AKSS of the GB group was higher than that of the MR group. The incidence of postoperative complications in the GB group (4.17%) was significantly lower than that in the MR group (18.75%) (P<0.05). Conclusion The GB technique can effectively shorten the operation time, relieve pain, improve knee range of motion, improve squat function and knee function, reduce osteoarthritis index, and reduce the occurrence of complications, which is worthy of clinical popularization and application.