Proximal tibial morphology and risk of posterior tibial cortex impingement in patients with AA-sized Oxford unicompartmental knee arthroplasty tibial implants

Table 2 Radiographic results

	Patient 1	Patient 2	Patient 3	Patient 4	Patient 5
Varus/valgus (°)	2.8°	2.3°	3.5°	2.6°	3.4°
Preop PSA^a (°)	7.9°	2.5°	4.9°	4.4°	3.9°
Postop PSA^a (°)	3.9°	3.1°	3.6°	3.1°	3.4°
Medial fit (mm)	1.26	1.55	1.34	1.2	0.23
Posterior fit (mm)	0	0.2	0.1	0	0
Anterior fit (mm)	− 1.27	1.16	0	0	− 1.3
Lateral fit (mm)	0	0.2	0	0.1	0
Depth of tibial saw cut (mm)	2.3	2.4	3.1	2.6	2.5
a/A	0.74	0.71	0.68	0.71	0.67
∠ R (°)	3.4	3.5	2.7	4.3	4.4
∠ M1 (°)	60.4	47.8	56.3	53.7	51.2
∠ M2 (°)	46.4	42.1	45.7	38.8	43.2
mDKC^b (mm)	3.58^*	8.54	5.19	5.41	6.31

All five patients fulfilled the correct component positioning criteria of Oxford Partial Knee Microplasty Instrumentation Surgical Technique
^aPSA: angle between the perpendicular line of the tibial intramedullary canal axis and the line connective anterior and posterior borders of the medial tibial plateau preoperatively or the line parallel to the tibial component surface postoperatively
^bmDKC: minimum distance between the tibial component keel and the outer margin of the posterior tibial cortex
^*< 4 mm: posterior tibial cortex at risk

ISSN: 1749-799X