Orkhan Aliyev1, Muzaffer Ağır1, Aghamazahir Aghazada1, Dilek Hacer Çeşme2, Deniz Kara1, Ali Toprak3, İbrahim Tuncay1, Fatih Yıldız4. 1. Department of Orthopaedics and Traumatology, Bezmialem Vakıf University, İskender Paşa Mh Adnan Menderes Bulvarı, Adnan Menderes Blv., 34093, Fatih/İstanbul, Turkey. 2. Department of Radiology, Bezmialem Vakıf University, Fatih/İstanbul, Turkey. 3. Department of Biostatistics and Medical Informatics, Bezmialem Vakıf University, İskender Paşa Mh Adnan Menderes Bulvarı, Adnan Menderes Blv., 34093, Fatih/İstanbul, Turkey. 4. Department of Orthopaedics and Traumatology, Bezmialem Vakıf University, İskender Paşa Mh Adnan Menderes Bulvarı, Adnan Menderes Blv., 34093, Fatih/İstanbul, Turkey. yildizfatih@hotmail.com.
Abstract
BACKGROUND: This retrospective study compares tibial component rotations and radiological and functional outcomes in patients who underwent Oxford medial unicompartmental knee arthroplasty (UKA), using the antero-posterior (AP) tibia axis or anterior superior iliac spine (ASIS) as the landmarks for the direction of the vertical cut. METHODS: A total of 86 patients, who underwent Oxford medial UKA were divided into 2 groups, each consisting of 43 patients, according to the use of AP axis (group I) or ASIS (group II) as landmarks for the rotation of vertical tibial cut and compared for the radiological and functional outcomes. Tibial component rotations (α-angle), involvement of the posterior cruciate ligament (PCL) fossa, and instant bearing position (IBP) were measured on computed tomography (CT) images. Functional outcomes were evaluated using Oxford knee score (OKS) and Knee Society score (KSS). RESULT: The median α‑angle was significantly smaller in group I than group II (2.5°, range -4-5.5° vs. -6°, range -13-0.5°, p < 0.001). The rates of PCL fossa involvements were 14 (32.6%) and 17 (39.5%, p = 0.7). The median flexion angle of the femoral component (7° vs. 10.5°) and posterior tibial slope (6° vs. 8°) were significantly lower in group I than group II (p = 0.001). All other radiological parameters, preoperative and final OKS and KSS were statistically similar in both groups. CONCLUSION: Taking the AP tibial axis as a landmark for vertical tibial cut rotation provides more neutral tibial component rotation in Oxford medial UKA compared to ASIS; however, this difference may not influence the clinical outcomes.
BACKGROUND: This retrospective study compares tibial component rotations and radiological and functional outcomes in patients who underwent Oxford medial unicompartmental knee arthroplasty (UKA), using the antero-posterior (AP) tibia axis or anterior superior iliac spine (ASIS) as the landmarks for the direction of the vertical cut. METHODS: A total of 86 patients, who underwent Oxford medial UKA were divided into 2 groups, each consisting of 43 patients, according to the use of AP axis (group I) or ASIS (group II) as landmarks for the rotation of vertical tibial cut and compared for the radiological and functional outcomes. Tibial component rotations (α-angle), involvement of the posterior cruciate ligament (PCL) fossa, and instant bearing position (IBP) were measured on computed tomography (CT) images. Functional outcomes were evaluated using Oxford knee score (OKS) and Knee Society score (KSS). RESULT: The median α‑angle was significantly smaller in group I than group II (2.5°, range -4-5.5° vs. -6°, range -13-0.5°, p < 0.001). The rates of PCL fossa involvements were 14 (32.6%) and 17 (39.5%, p = 0.7). The median flexion angle of the femoral component (7° vs. 10.5°) and posterior tibial slope (6° vs. 8°) were significantly lower in group I than group II (p = 0.001). All other radiological parameters, preoperative and final OKS and KSS were statistically similar in both groups. CONCLUSION: Taking the AP tibial axis as a landmark for vertical tibial cut rotation provides more neutral tibial component rotation in Oxford medial UKA compared to ASIS; however, this difference may not influence the clinical outcomes.