Table 1.

Indications for UKA, HTO, and overlaps between treatments.

	UKA	HTO or UKA	HTO
Age	>55 years	55–65 years	<65 years
Activity level	Low demands	Moderately active	Active
Weight (BMI)	<30	Any
Alignment	0–5°	5–10°	5–15°
AP instability	No to grade I	No to grade I	Any
ML instability	No to grade I	No to grade I	No to grade II
ROM	Arc 90° and <5° flexion contracture	Arc 100° and <5° flexion contracture	Arc 120° and <5° flexion contracture
Arthrosis severity	Any	Ahlback II	Ahlback I-II

UKA = medial unicompartmental knee arthroplasty; HTO = high tibial osteotomy; BMI = body mass index; AP instability = anteroposterior instability; ML instability = mediolateral instability; instability grading: according to the American Medical Association (grade I = 0–5 mm; grade II = 5–10 mm; grade III = >10 mm; no hard stop); arthrosis severity = medial compartment arthrosis according to Ahlback classification, assuming that lateral and patellofemoral compartments are intact.