Tension Band Plate (TBP)-guided Hemiepiphysiodesis in Blount Disease: 10-Year Single-center Experience With a Systematic Review of Literature.

BACKGROUND: Primary treatment for Blount disease has changed in the last decade from osteotomies or staples to tension band plate (TBP)-guided hemiepiphysiodesis. However, implant-related issues have been frequently reported with Blount cases. The purpose of our study is to evaluate the surgical failure rates of TBP in Blount disease and characterize predictors for failure.

METHODS: We performed an Institutional Review Board-approved retrospective chart-review of pediatric patients with Blount disease to evaluate the results of TBP from 2008 to 2017 and a systematic literature review. Blount cases defined as pathologic tibia-vara with HKA (hip-knee-ankle) axis and MDA (metaphyseal-diaphyseal angle) deviations ≥11 degrees were included in the analysis. Surgical failure was categorized as mechanical and functional failure. We studied both patient and implant-related characteristics and compared our results with a systematic review.

RESULTS: In 61 limbs of 40 patients with mean follow-up of 38 months, we found 41% (25/61) overall surgical failure rate and 11% (7/61) mechanical failure rate corresponding to 11% to 100% (range) and 0% to 50% (range) in 8 other studies. Statistical comparison between our surgical failure and nonfailure groups showed significant differences in deformity (P=0.001), plate material (P=0.042), and obesity (P=0.044) in univariate analysis. The odds of surgical failure increased by 1.2 times with severe deformity and 5.9 times with titanium TBP in the multivariate analysis after individual risk-factor adjustment. All 7 mechanical failures involved breakage of cannulated screws on the metaphyseal side.

CONCLUSIONS: Most of the studies have reported high failure rates of TBP in Blount cases. Besides patient-related risk factors like obesity and deformity, titanium TBP seems to be an independent risk factor for failure. Solid screws were protective for mechanical failure, but not for functional failure. In conclusion, efficacy of TBP still needs to be proven in Blount disease and implant design may warrant reassessment.

LEVEL OF EVIDENCE: Level III-retrospective comparative study with a systematic review.