Opening wedge high tibial osteotomy for medial compartment knee osteoarthritis: Planning and improving outcomes: Case series and literature review.

Background: Opening wedge high tibial osteotomy (OWHTO) is a safe surgical procedure to treat medial compartmental osteoarthritis caused by a varus deformity. Over-correction of this varus deformity can lead to lateral compartment over-loading. In our study, we planned our correction by using the mechanical axis deviation (MAD). Purpose: The purpose of this study is to evaluate the clinical and radiological results of OWHTO based on planning using the MAD measurements. Study Design: Retrospective Case Series. Methods: 14 patients with Kellgren- Lawrence classification (KL) grade 3 or above underwent OWHTO, with plans to have the mechanical axis pass through 5-15 mm lateral to the center of the tibial plateau. Pre-operative and post-operative radiographic measurements were made and compared using the student t-test. SF-36 scores were obtained for clinical performance. Results: Our patients experienced MAD from 25.9 mm medial to the center of the tibial plateau pre-operatively to 12.7 mm lateral to the center of the plateau post-operatively. The mean change in MAD was 38.7 mm (p < 0.0001). The accuracy of our correction compared to the planned MAD was 98.3%. The mechanical axis angle shifted from 7.35° of varus to 3.5° of valgus (p < 0.0001). All patients had post-operative alignments of 1-6° of valgus, with 11 of out the 14 patients with alignments less than 5° of valgus, preventing over-loading of the lateral compartment. Conclusion: Using MAD measurements is an accurate planning method for OWHTO that corrects varus deformity without over-loading the lateral compartment, and leads to improved clinical outcomes.

STRYDE versus PRECICE magnetic internal lengthening nail for femur lengthening.

INTRODUCTION: Magnetic internal lengthening nails (MILNs) have been used for femoral lengthening to avoid complications associated with external fixation. The titanium version of the MILN (PRECICE®) has been in use since 2011 but had limitations (50-75 lb) in post-operative weight bearing. A new stainless-steel version of the MILN (STRYDE®) allows 150-250 lb of post-operative weight bearing. The aim is to compare the outcomes of using these two different MILNs for both unilateral and bilateral femoral lengthening. METHODS: A single-center, retrospective cohort study was conducted in which patients' records were reviewed from the period from January 2017 to March 2020. A total of 66 femoral lengthening procedures were included in the study and were divided into two groups: STRYDE® group (30 femora) and PRECICE® group (36 femora). Outcomes assessed were the 6-months post-operative Limb Deformity-Scoliosis Research Society (LD-SRS) Score, adjacent joint range of motion (ROM), average distraction rate, bone healing index (BHI), and complications. RESULTS: No statistically significant difference was found between the two groups in regard to the (LD-SRS) score, hip ROM, or knee ROM. Statistically significant differences were found between the two groups in regard to BHI (average of 0.84 months/cm and 0.67 months/cm for STRYDE® and PRECICE®, respectively) and distraction rate (average of 0.6 mm/day and 0.9 mm/day for STRYDE® and PRECICE®, respectively). No mechanical nail complications were reported in the STRYDE® group compared to three events of nail failure in the PRECICE® group. One femur in the PRECICE® group needed BMAC injection for delayed healing compared to four femurs in the STRYDE® group. CONCLUSION: The STRYDE® MILN yields comparable functional results to those of PRECICE® MILN and shows fewer mechanical nail complications. However, STRYDE® MILN requires a slower distraction rate and yields slower healing (larger BHI). LEVEL OF EVIDENCE: Level III, Therapeutic study.

Humerus Lengthening: A Comparison of the Internal Lengthening Nail to External Fixation.

Introduction: Magnetic internal lengthening nails (MILNs) have been used for humeral lengthening to avoid complications associated with external fixation. Purpose/Questions: We compared the 1-year Disabilities of the Arm, Shoulder and Hand (DASH) score, adjacent joint range of motion (ROM), bone healing index (BHI), length achieved, distraction rate, and complications when lengthening the humerus using MILN vs using external fixation. Methods: We conducted a retrospective cohort study of 18 patients (22 humeri) from January 2001 to March 2020 divided into 2 groups, the MILN group (7 patients, 7 humeri) and the mono-lateral fixator group (11 patients, 15 humeri). Results: The MILN group showed larger improvement of DASH scores (average 26.8 and 8 for MILN and fixator groups, respectively), less loss of elbow ROM (average 5° and 7° for MILN and fixator groups, respectively), and shorter time to full recovery of elbow ROM (average 39 days and 122 days for MILN and fixator groups, respectively). In the MILN group, there was slower distraction rate (average 0.66 mm/day and 0.86 mm/day for MILN and fixator groups, respectively), less lengthening achieved (average 5.2 cm and 7 cm for MILN and fixator group, respectively), and a lower lengthening percentage (average 19% and 41% for MILN and fixator group, respectively). Bone healing index (BHI) of 0.94 and 0.99 months/cm for the MILN and the fixator groups were similar. Conclusion: Humeral lengthening using the MILN allowed for early full recovery of joint ROM with comparable functional and radiographic outcomes compared with using external fixators.