The Effect of Tibiotalar Joint Line Level Alterations on Tibiotalar Range of Motion Following Total Ankle Arthroplasty

Abstract

Background: The effect of tibiotalar joint line level (TTJL) on patient outcomes following total ankle arthroplasty (TAA) remains unclear. It was previously reported that patients with end-stage ankle arthritis have an elevated TTJL compared with nonarthritic ankles, and the TTJL post-TAA remains elevated compared with nonarthritic ankles. The objectives of this study were to (1) propose a reliable radiographic method to measure the TTJL absolute value and (2) determine the effect of TTJL alterations on tibiotalar range of motion (ROM) following TAA. Methods: A retrospective review was performed on patients who underwent TAA between January 2018 and April 2021 with a minimum of 1-year postoperative follow-up and complete perioperative ROM radiographs. Radiographic TTJL and ROM measurements were performed by 2 observers. The proposed TTJL measuring technique computes 4 measurements: high, low, center of the talus (center), and center of the axis (axis). Reliability of measurements and correlation between TTJL measurements and ROM were assessed. Results: A total of 33 patients were included. Postoperatively, 22 patients had a lowered TTJL compared to 11 patients with an elevated TTJL (2.2 ± 1.3 mm lowered vs 1.9 ± 1.2 mm elevated; P < .0001). Of the 4 TTJL measurements, 3 (low, center, axis) demonstrated a significant positive correlation between lowering the TTJL and improved tibiotalar dorsiflexion and 2 (low, axis) for total ROM (all P < .05). Plantarflexion was not significantly affected by TTJL alterations. Compared to patients with an elevated TTJL, patients with a lowered TTJL had improved tibiotalar dorsiflexion (8.8 vs 2.5 degrees; P = .0015) and total ROM (31.0 vs 22.9 degrees; P = .0191), respectively. The interrater reliability was nearly perfect (intraclass correlation r = 0.96-0.99). Conclusion: In this small series, we found that lowering the TTJL level may more closely reestablish the native TTJL and correlates with improved tibiotalar dorsiflexion and total ROM following TAA. Level of Evidence: Level IV, case series.

Range of Motion After Total Ankle Replacement: Are We Just Stuck?

“…Cenni et al 3 suggested that some component malpositioning may be tolerated without diminishing ROM. With an evolving interest in patient-specific surgery, perhaps a future consideration may be preoperatively CT-planned, ligament-compatible custom 3D-printed TAA implanted with patient-specific instrumentation, as suggested by Faldini et al 5 In their studies of fixed-bearing TAA, Palma et al 12 and Fletcher et al 6 surmised that reestablishing the anatomic joint line may in turn reestablish the physiologic function through improved retensioning of the ankle's external muscle myotendinous units and length-force relationships. Valderrabano et al 15 compared muscle function, including ROM, preoperatively and at 1-year follow-up for 15 patients undergoing mobile-bearing TAA.…”

“…8 In joint line level considerations for TAA, as for most foot and ankle pathologies, more information is needed. Palma et al 12 and Fletcher et al 6 acknowledged that the joint line level may be difficult to analyze as an independent variable and that ankle function and ROM following TAA have multifactorial influences. As fellow investigators, we are excited to see 2 independent investigative teams arrive at the same consideration to broaden our understanding of TAA.…”

“…Despite Palma et al 12 and Fletcher et al 6 offering distinctly different methods of measuring joint line level for TAA, the similarities in background, results, and conclusions are uncanny. Both investigative groups extrapolated from total knee arthroplasty (TKA) research indicating elevation of the TKA joint line leads to worse ROM than if the physiologic joint line is restored.…”

“…In the majority of ankle arthritis cases, the relatively weaker tibia plafond tends to erode more rapidly than the denser talar dome, leading to elevation of the joint line. 1,7,10,11 Given that our anecdotal practices to optimize postoperative TAA ROM fall short in restoring physiologic motion, we read with great interest 2 similar manuscripts by Palma et al 12 and Fletcher et al 6 reporting on the influence of the tibial joint line levels on TAA ROM. Although these investigative teams suggested that their retrospectively collected evidence was admittedly "modest" and with only "weak correlation," each independently demonstrated that restoring the tibial joint line with TAA to a more anatomic superior/inferior level results in better ankle dorsiflexion compared to an elevated joint line.…”

“…In their studies of fixed-bearing TAA, Palma et al 12 and Fletcher et al 6 surmised that reestablishing the anatomic joint line may in turn reestablish the physiologic function through improved retensioning of the ankle’s external muscle myotendinous units and length-force relationships. Valderrabano et al 15 compared muscle function, including ROM, preoperatively and at 1-year follow-up for 15 patients undergoing mobile-bearing TAA.…”