Combined femoral and tibial component total knee arthroplasty device rotation measurement is reliable and predicts clinical outcome.

BACKGROUND: The optimal total knee arthroplasty (TKA) rotational alignment and how best to obtain and measure it are debatable. The aim was to analyse the reliability of the Berger femoral, three different tibial and four different combined two-dimensional computer tomography (2D-CT) TKA component rotation measurements, and to ascertain which rotational values best predict a successful clinical outcome. METHODS: The 2D-CT scans were obtained post-operatively on 60 patients who had TKA. We determined one femoral [Berger's femoral angle (BFA)], three tibial [Berger's tibial angle (BTA), anatomical tibial angle (ATA) and bimalleolar posterior tibial component angle (BM_PTCA)] and four combined [transepicondylar posterior tibial component angle (TE_PTCA), bicondylar posterior tibial component angle (BC_PTCA, transepicondylar bimalleolar angle (TE_BM) and bicondylar bimalleolar angle (BC_BM)] TKA rotation angles. We made all measures in 23 patients twice by three observers and determined inter- and intra-observer agreement using the Bland-Altman plot method. We analysed measures of 55 patients using the area under the ROC curve (AUC) analysis to ascertain the discriminative capacity of BFA, ATA, TE_PTCA and BC_PTCA for predicting a successful clinical outcome according to the Knee Society Score (KSS) threshold. RESULTS: ATA showed the smaller inter- and intra-observer average of differences (-0.1° and 1.6°, respectively) of the studied methods followed by BFA (-0.9° and 1.4°), TE_PTCA (-2.1° and 2.7°) and BC_PTCA (-0.5° and 1.8°). BFA (-4° to 2.1° and -6.1° to 8.8°) and BC_PTCA (-4.4° to 3.4° and -7.9° to 4.4°) showed the narrower inter- and intra-observer limits of agreement. A TKA device rotation (BC_PTCA) < 0.8° of external rotation (ER) predicted a KSS and KSS knee successful outcome, and < 3.8° ER for KSS functional (AUC = 0.889; 0.907 and 0.764, respectively). BFA and ATA < 0.9° ER and < 3.9° internal rotation (IR) predicted a successful KSS knee outcome (AUC = 0.796 and 0.889, respectively). CONCLUSION: The ATA tibial component rotation measurement was the most reliable of those studied. BFA, TE_PTCA and BC_PTCA were reliable measures for TKA femoral and combined rotation. The presence of a minimal rotation between the TKA components (BC_PTCA) and a small femoral ER or tibial IR predicted a successful KSS outcome.

Revisiting the original Akin technique: A comparative analysis of radiographic outcome.

BACKGROUND: The Akin osteotomy is widely used to correct the hallux valgus and different fixation techniques have been proposed. Currently most of these procedures coexist, with disagreement on which offers the best results. The aim of this study is to compare the radiological outcome of the original Akin's technique with one in which a staple was used to stabilize the osteotomy. We also assessed whether other factors unrelated to the osteosynthesis could influence the radiological outcome. METHODS: We retrospectively reviewed data from 118 patients who underwent a scarf and Akin osteotomy. In 60 patients the Akin osteotomy was fixed with a staple and in 58 cases no staple was used. Hallux valgus angle (HVA), distal articular set angle (DASA), interphalangeal angle (IPA) and tibial sesamoid position were measured. The presence of lateral cortex disruption of the phalanx was also included in the analysis. RESULTS: Six variables significantly influenced the radiological results of the Akin osteotomy: preoperative HVA, IPA and tibial sesamoid position, laterality, postoperative cortical disruption and use of a staple. CONCLUSION: Ours results suggest that the original Akin's technique seems to offer equal or better results than a variation in which a staple is added to stabilize the osteotomy. LEVEL OF EVIDENCE: This is a level III retrospective case-control study.