Feasibility and 3D Planning of a Novel Patient-Specific Instrumentation Technique in Medial Opening-Wedge High Tibial Osteotomy

A novel approach for opening-wedge high tibial osteotomy (OWHTO) with patient-specific instrumentation (PSI) was evaluated for its safety, feasibility, and accuracy. Next, the mechanical medial proximal tibial angle (mMPTA) was assessed as a potential planning angle by investigating the relation with the mechanical femorotibial angle (mFTA). Ten OWHTO cases were 3D planned using the mMPTA and operated with a customized 3D-printed wedge and cast which resembled the intended osteotomy opening. Patients were closely monitored for intraoperative and postoperative complications up to 1 year after surgery. Radiological assessment was conducted on full leg standing radiographs and supine lower limb computed tomography-scans preoperatively and 3 months after surgery. No intraoperative complications or logistical issues during PSI processing were observed. Absolute accuracy outcomes showed a correction error of 1.3° ± 1.1 mMPTA and 0.9° ± 0.6 mFTA with all osteotomies falling in (-2°; + 2°) mFTA around the target. The mMPTA and mFTA were found to have a strong correlation in both 3D (r = 0.842, p = 0.002) and 2D (r = 0.766, p = 0.01) imaging for effective correction. The study confirmed the development of a safe and feasible PSI technique in OWHTO with excellent accuracy outcomes. The strong correlation between the mMPTA and mFTA indicated that soft tissue changes after OWHTO are of minor significance to the final alignment in ligament-stable patients. Finally, the mMPTA was found to be a reliable planning angle in 3D software for obtaining the intended lower limb realignment and its use can therefore be recommended in modern OWHTO planning.

Structural allograft impaction enables fast rehabilitation in opening-wedge high tibial osteotomy: a consecutive case series with one year follow-up

PURPOSE

Painful and slow recovery are the presumed disadvantages after opening-wedge high tibial osteotomy (HTO) and play a role in favouring arthroplasty as treatment for moderate isolated medial knee arthritis. The primary study objective was to investigate the effect of press-fit structural impacted bone allograft with locking plate fixation on early ambulation, postoperative pain levels, and resumption of daily-life activities in opening-wedge HTO.

METHODS

A prospective consecutive opening-wedge HTO case series was conducted, including 103 patients with final follow-up at 1 year. Weight-bearing was allowed from the day after surgery "as tolerated" by the patient. Clinical assessment included the Numeric Rating Scale (NRS), Knee injury and Osteoarthritis Outcome Score (KOOS), and Lysholm score. Additionally, the Knee Society Score (KSS) was assessed during consultation at 1, 3, and 12 months postoperatively with special attention for clinical anchor questions. Required sample size was calculated and a linear mixed-effect model was used for repeated measures over time of the clinical scores.

RESULTS

The NRS decreased by 1.5 at 1 month (p < 0.01) and 2.1 at 3 months (p < 0.01), while KOOS pain significantly improved with 19.2 (p < 0.01) by this time compared to baseline. Under reduced pain levels, 98% were able to walk > 500 m without support, while all patients were able to climb up and down the stairs 3 months postoperatively.

CONCLUSION

The study strongly supports the initial hypothesis that applying structural triangular bone allograft in HTO leads to low postoperative pain levels, early ambulation, and excellent short-term clinical outcomes. Study results have the potential to alter the general perception about HTO being a painful procedure with painstakingly slow recovery and consequently encourage the consideration of HTO as a highly valuable joint-preserving option, while treating unicompartmental knee arthritis.

LEVEL OF EVIDENCE

IV (case series).