Progression of medial compartmental osteoarthritis after a valgus high tibial osteotomy.

Gorter, J. (Jelle) (2014) Progression of medial compartmental osteoarthritis after a valgus high tibial osteotomy. thesis, Medicine.

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Abstract

Background: Unicompartmental osteoarthritis (OA) of the knee occurs mostly in the medial compartment and often has a mechanical cause. Loss of cartilage in the medial compartment results in varus deformity of the knee, shifting the mechanical axis to the medial compartment, thereby increasing the load bearing on the already vulnerable compartment. Patients are often relatively young; therefore total knee replacement is not the treatment of choice. A closing-wedge high tibial osteotomy (HTO) creates a valgus alignment of the knee, shifting the mechanical axis and the load bearing to the lateral compartment. The clinical outcome is good, but results tend to deteriorate over time. The effect of HTO surgery on the progression of OA is not yet fully understood. This study was aimed to assess if HTO surgery can restrain or even stop the progression of OA in the mid term. Second of all the effect of HTO surgery on clinical outcome was assessed, and preoperative risk factors for early failure were analyzed. Materials and methods: 314 patients were followed in a prospective cohort study. All patients were treated with HTO surgery for symptomatic medial compartment OA between January 2006 and December 2011, by a single surgeon. Before surgery and at the time of the follow-up all patients were asked to fill out Western Ontario and McMaster Universities Arthritis Index (WOMAC) score and numerical rating scale (NRS) score for pain for clinical outcome (e.g. pain, stiffness and physical functioning). Preoperatively and postoperatively standard weight bearing anterior-posterior (AP) radiographs of the knee were made, and a lateral radiograph in 30° flexion. Measurement of progression was done by comparing the Kellgren-Lawrence (KL) score and minimum joint space width (mJSW) pre- and postoperatively. Follow-up ranged from 3-8 years. Failure was defined as revision surgery (e.g. conversion to total knee arthroplasty (TKA) or revision osteotomy). Preoperative risk factors for early failure were identified using Cox regression analysis. Results: The mean preoperative mJSW was 3,39 ± 1,55mm and changed to 3,35 ± 1,67mm postoperatively, which was not significant (p=0,51). Mean annual joint space narrowing was 0,0189 mm/year. Preoperative KL-scores vary between KL 1 and KL 4, distributed as KL 1=110 (35%), KL 2=153 (48%), KL 3=46 (15%) and KL 4=5 (2%), which changed to KL 1=48 (15%), KL 2=129 (41%), KL 3=114 (37%) and KL 4=23 (7%) (p0,001). No KL progression was seen in 51%. Mean NRS decreased from 7,28 ± 1,51 to 3,48 ± 2,50 (p<0,001). WOMAC-scores changed from 47,97 ± 17,22 to 23,60 ± 19,68 (p<0,001). Failure was seen in 30 cases. The risk factors associated with early failure were: female gender, age≥50 and preoperative HKA angle. Conclusion: HTO surgery is an effective treatment for medial compartmental OA, and a good option for delaying TKA. Annual joint space narrowing was 0,0189 mm/year which is lower than reported means from other studies who estimate JSN without treatment between 0,05 and 0,13 mm/yr. About half of our patients had an increased mJSW. Despite progression of KL scores, significant functional improvement and no relevant joint space change after several years indicate that HTO surgery is effectively able to curtail and for some patients temporarily arrest OA progression.

Item Type:	Thesis (Thesis)
Supervisor name:	Brouwer, Dr. R.W. and Huizinga, Drs. M. and Martini Hospital Groningen
Faculty:	Medical Sciences
Date Deposited:	25 Jun 2020 10:43
Last Modified:	25 Jun 2020 10:43
URI:	https://umcg.studenttheses.ub.rug.nl/id/eprint/424

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