Distal Femoral Osteotomy Survivorship: A Population-based Study

Abstract

Objectives:

Malalignment of the lower extremity can lead to functional impairment and degenerative changes at an early age. Distal femoral osteotomies (DFO) are often performed concurrently with arthroscopic procedures to correct malalignment while addressing intra-articular pathology. The aim of this study was to examine survivorship following distal DFO and to identify risk factors for failure.

Methods:

Data from the California Office of Statewide Health Planning and Development, a mandatory statewide discharge database, was utilized to identify all patients who underwent a DFO from 2000 to 2014. Patients with lower extremity trauma, infectious arthritis, rheumatologic disease, congenital deformities, malignancy, or concurrent arthroplasty were excluded. Patient demographic information was assessed for every patient. Failure was defined as conversion to total or unicompartmental knee arthroplasty. Statistically significant differences between patients who required arthroplasty and those who did not were identified on univariate analysis. A multivariate analysis was performed to account for identified differences and a survivorship curve was constructed to estimate 5 and 10-year survivorship.

Results:

After exclusions were applied, 420 patients were identified and followed for an average of 5.0 years. Of those, 53 were converted to arthroplasty at an average of 5.9 years. 5-year survivorship was 98.3% and 10-year survivorship was 92.3%. Patients converted to arthroplasty tended to be older (43.6 years versus 36.9 years, p<0.001) and had a higher number of comorbidities (47.2% with at least one comorbidity versus 27.5%, p=0.021). A diagnosis of osteoarthritis at the time of surgery was more prevalent amongst patients who went on to arthroplasty (81.1% versus 53.7%, p<0.001). On multivariate analysis, patients were 4% more likely to undergo arthroplasty for each additional year of age (OR 1.04, p=0.013). Patients with osteoarthritis were also at increased risk of conversion to arthroplasty (OR 2.57, p=0.025).

Conclusion:

Older age and a diagnosis of osteoarthritis at the time of surgery were associated with conversion to arthroplasty. These factors should be taken into account when performing this procedure.

Table 1:

Patient Demographics

	Total Cohort		Arthroplasty		Non-arthroplasty		p-value
	420	100.00%	53	10.10%	367	69.90%
Age	37.72	SD=11.06	43.60	SD=8.88	36.87	SD=11.10	<0.001
Sex
Male	188	44.76%	22	41.51%	166	45.23%	0.610
Female	232	55.24%	31	58.49%	201	54.77%
Race
White	244	58.10%	28	52.83%	216	58.86%	0.186
Black	38	9.05%	4	7.55%	34	9.26%
Hispanic	69	16.43%	7	13.21%	62	16.89%
Asian	15	3.57%	1	1.89%	14	3.81%
Other	12	2.86%	3	5.66%	9	2.45%
Missing	42	10.00%	10	18.87%	32	8.72%
Comorbidities
Obesity	46	10.95%	4	7.55%	42	11.44%	0.488
Hypertension	57	13.57%	17	32.08%	40	10.90%	<0.001
Diabetes meilitus	10	2.38%	2	3.77%	8	2.18%	0.366
Depression	13	3.10%	3	5.66%	10	2.72%	0.218
Asthma	45	10.71%	9	16.98%	36	9.81%	0.115
CKD	3	0.71%	0	0.00%	3	0.82%	1.000
CHF	1	0.24%	0	0.00%	1	0.27%	1.000
Number comorbidities
None	294	70.00%	28	52.83%	266	72.48%	0.021
One	89	21.19%	18	33.96%	71	19.35%
Two	26	6.19%	4	7.55%	22	5.99%
Three	10	2.38%	3	5.66%	7	1.91%
Four	1	0.24%	0	0.00%	1	0.27%
Diagnosis Category
Osteoarthrosis	240	57.14%	43	81.13%	197	53.68%	<0.001
Genu valgum (acquired)	111	26,43%	13	24.53%	98	26.70%	0.737
Other acquired deformity	121	28.81%	18	33.96%	103	28.07%	0.376
Derangement of internal structures	75	17.86%	10	18.87%	65	17.71%	0.837
Osteochondral defect	61	14.52%	4	7.55%	57	15.53%	0.146
Traumatic arthropathy	10	2.38%	2	3.77%	8	2.18%	0.366
Other arthropathy	56	13.33%	1	1.89%	55	14.99%	0.009
Concurrent Procedures
Arthroscopy	66	15.71%	6	11.32%	60	16.35%	0.347
Osteochondral graft	89	21.19%	13	24.53%	76	20.71%	0 525
Synovectomy	16	3.81%	2	3.77%	14	3.81%	1.000
Meniscectomy	48	11.43%	6	11.32%	42	11.44%	1.000