Which lumbar vertebra should be the lowest level of fusion in adolescent idiopathic scoliosis of Lenke types 5 and 6?

OBJECTIVE:  It is important to protect the mobile segment in the lumbar region in scoliosis surgery. The aim of this study was to compare the clinical and radiological results of patients who underwent surgery for a diagnosis of adolescent idiopathic scoliosis (AIS) with the lowest instrumented vertebra (LIV) at L3 or L4 level. METHODS:  The study included 36 patients who underwent surgical treatment in our institution for a diagnosis of Lenke type 5 and 6 AIS with a follow-up period of at least 24 months. The patients were separated into 2 groups according to the LIV level of L3 (n=21) and L4 (n=15). These 2 groups were compared preoperatively (PO), early postoperative (EPO), and at the final follow-up examination (last control (LC)) with respect to radiological parameters in the coronal and sagittal planes, and the Scoliosis Research Society - 22 (SRS-22) questionnaire values. RESULTS:  In both groups the mean age (L3: 16 ± 7.3; L4: 17 ± 6.1 years) and follow-up periods (L3: 44 ± 20; L4: 47 ± 18 months) were similar. Radiologically, the L4 group had a greater Cobb angle in the scoliosis main curves measured PO (P=.001). The Cobb angles measured at EPO (P=.767) and at LC (P=.674) were similar in both groups. No significant difference was observed between the 2 groups in respect of the LIV tilt values at PO (P=.469), EPO (P=.297), and LC (P=.065). When the groups were evaluated separately, the LIV tilt values at EPO and LC were similar in the L4 group (EPO: 6.93 ± 3.058; LC: 7.26 ± 2.313; P=.618). In the L3 patients, although there seemed to be a significant increase in LIV tilt values when EPO values were compared with LC values (EPO: 8.47 ± 3.970; LC: 9.57 ± 3.76; P=.030), this was within the error range of Cobb angle measurement. The results of the SRS-22 questionnaire showed significantly better results in the L3 group in the domains of pain, function/activity, mental health, and satisfaction with treatment (P=.011, P=.002, P=.019, P=.046, respectively). CONCLUSION:  There was no radiological superiority between L3 and L4 LIV groups in the thoracolumbar/lumbar curve patients. However, according to the SRS-22 questionnaire, the results of patients with L3 level LIV were better in the areas of pain, function/activity, mental health, and satisfaction with treatment. Cite this article as: Baymurat AC, Tokgoz MA, Abdulaliyev F, Tosun MF, Can MM, Senkoylu A. Which lumbar vertebra should be the lowest level of fusion in adolescent idiopathic scoliosis of Lenke types 5 and 6? Acta Orthop Traumatol Turc., 2024;58(2):116-123.

Gerdy's tubercle as a novel anatomical landmark for the proximal tibial cut in total knee arthroplasty.

OBJECTIVES: This study aimed to explore the use of Gerdy's tubercle (GT) as an innovative and dependable anatomical landmark for the proximal tibial cut in total knee arthroplasty (TKA) in cases with extensive knee degeneration. MATERIALS AND METHODS: One hundred dry tibia bones and 10 formalin-fixed cadaveric knee specimens of both sexes were examined. A Zimmer NexGen tibial cutting guide and a Mitutoyo digital caliper were utilized to align the guide with the tibia's mechanical axis. The procedure was replicated on cadaver knees using a standardized medial parapatellar arthrotomy approach. Measurements included the distance from GT superior border to the resection line and the length of the tibia. A radiological study involving magnetic resonance imaging examinations of 48 patients, which were evaluated focusing on the upper border of GT and the least degenerated segment of the posterolateral part of the lateral tibial condyle, was conducted. RESULTS: Anatomical measurements of GT and proximal tibial areas in 110 specimens showed slight but consistent variations with cadaver measurements. Magnetic resonance imaging analysis of 48 patients revealed notable sex differences in the distance between the superior border of GT and the tibia's posterolateral surface. There was also a significant negative correlation between the distance from GT to the posterolateral corner and cartilage thickness. CONCLUSION: Proper alignment in TKA is crucial for success, but identifying an extra-articular landmark for horizontal tibial resection remains challenging, particularly in severely arthritic knees. This study introduces GT as a novel anatomical landmark for TKA, offering a more reliable reference for achieving desired joint levels in knees with significant degenerative changes.