STRYDE versus PRECICE magnetic internal lengthening nail for femur lengthening

Abstract

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.

A clinical and radiological matched-pair analysis of patients treated with the PRECICE and STRYDE magnetically driven motorized intramedullary lengthening nails

“…26 Based on the calculated odds in this study, implant failure was more likely in the STRYDE cohort. While Galal et al 14 and Robbins and Paley 7 did not mention implant failure, most studies concerning the STRYDE nail have reported on implant failures comparable to our results. 8,10,21,23,24 This finding appears to be specific to the STRYDE nail since neither we nor previous studies observed nail or locking bolt breakage as a common complication in patients treated with the conventional PRECICE nail.…”

“…There was no relevant difference in terms of distraction and consolidation indices between the STRYDE and PRECICE cohort, in contrast to the results of Galal et al, 14 who reported a statistically significant lower distraction rate and a statistically significant higher bone healing index for their STRYDE compared to their PRECICE cohort. However, bone healing seemed to be affected in patients treated with the STRYDE nail in our cohort, since these patients were more likely to undergo revision surgery due to delayed consolidation in comparison to the PRECICE cohort.…”

“…However, bone healing seemed to be affected in patients treated with the STRYDE nail in our cohort, since these patients were more likely to undergo revision surgery due to delayed consolidation in comparison to the PRECICE cohort. This observation is supported by Galal et al, 14 who reported delayed consolidation as a relatively frequent finding in their STRYDE cohort, and others who reported on insufficient bone regenerates of segments lengthened with the STRYDE nail. 8,23 It could be speculated that the cause of this is the stiff design of the STRYDE nail, which might impair bone healing due to less micromovement.…”

“…Previous studies have reported contradictory results regarding full weightbearing during lengthening with the STRYDE nail. While Rölfing et al 10 found that not all patients treated with the STRYDE nail were able to bear full weight during treatment, Galal et al 14 and Robbins and Paley 7 did not report difficulties with full weightbearing. However, these two studies were published before STRYDE-specific complications were known and therefore limited mobility due to implant-related problems might not have been recorded.…”

“…8-12 Several studies reported complications associated with the STRYDE nail, 8,11,12 and a recent report has explored the natural history of focal osteolyis. 13 However, few studies compare the clinical and radiological outcome of patients treated with the STRYDE or PRECICE nail, 14,15 and the clinical differences with a follow-up of more than one year remain to be reported. In this single-centre matched-pair analysis, we focus on the comparison of these two intramedullary lengthening devices and aim to clarify any clinical and radiological differences.…”