The human knee is designed to carry load evenly across both its inner (medial) and outer (lateral) compartments. When the mechanical axis of the leg — the line running from the centre of the hip to the centre of the ankle — passes through one compartment rather than the middle of the joint, load is concentrated unevenly. Over time, this asymmetric loading accelerates cartilage wear in the overloaded compartment and can drive the development of osteoarthritis in otherwise healthy knees.
Osteotomy is a surgical procedure that corrects this malalignment by cutting and repositioning the tibia or femur to shift the mechanical axis back towards the centre of the joint. By doing so, load is redistributed away from the damaged compartment, pain is relieved, and the progression of arthritis is slowed or halted. In the right patient, osteotomy can defer or entirely avoid the need for joint replacement.
The procedure is most effective in younger, active patients with unicompartmental arthritis and a correctable deformity. Thorough pre-operative planning — including long-leg standing X-rays to measure the mechanical axis precisely — is essential to achieving the correct degree of correction. Too little correction fails to unload the affected compartment; too much shifts the problem to the opposite side of the joint.
Recovery following osteotomy requires a period of protected weight-bearing while the bone heals, typically six to twelve weeks, followed by a structured physiotherapy programme. Most patients return to low-impact activity within three to four months and to more demanding pursuits within six to nine months. For patients who go on to require knee replacement in later years, a previous osteotomy is not a barrier to that surgery, although the earlier correction does need to be taken into account when the replacement is planned.
