European Spine Journal

, Volume 21, Supplement 5, pp 592–598

Resect or not to resect: the role of posterior longitudinal ligament in lumbar total disc replacement

  • Balkan Cakir
  • Marcus Richter
  • Werner Schmoelz
  • René Schmidt
  • Heiko Reichel
  • Hans Joachim Wilke
Original Article

DOI: 10.1007/s00586-009-1193-4

Cite this article as:
Cakir, B., Richter, M., Schmoelz, W. et al. Eur Spine J (2012) 21(Suppl 5): 592. doi:10.1007/s00586-009-1193-4

Abstract

With regard to the literature, several factors are considered to have an impact on postoperative mobility after lumbar total disc replacement (TDR). As TDR results in a distraction of the ligamentous structures, theoretically the postoperatively disc height and ligamentous integrity have also an influence on biomechanics of a treated segment. The purpose of the study was to evaluate the influence of posterior longitudinal ligament (PLL) resection and segmental distraction on range of motion (ROM). Six human, lumbar spines (L2–L3) were tested with pure moments of ±7.5 Nm in a spine loading apparatus. The ROM was determined in all three motion planes. Testing sequences included: (1) intact state, (2) 10 mm prosthesis (PLL intact), (3) 10 mm prosthesis (PLL resected), (4) 12 mm prosthesis (PLL resected). The prosthesis used was a prototype with a constrained design using the ball-and-socket principle. The implantation of the 10 mm prosthesis already increased the disc height significantly (intact: 9.9 mm; 10 mm prosthesis: 10.6 mm; 12 mm prosthesis: 12.7 mm). Compared to the intact status, the implantation of the 10 mm prosthesis resulted in an increase of ROM for flexion/extension (8.6° vs 10.8°; P = 0.245) and axial rotation (2.9° vs 4.5°; P = 0.028), whereas lateral bending decreased (9.0° vs 7.6°; P = 0.445). The resection of the PLL for the 10 mm prosthesis resulted in an increase of ROM in all motion planes compared to the 10 mm prosthesis with intact PLL (flexion/extension: 11.4°, P = 0.046; axial rotation: 5.1°, P = 0.046; lateral bending: 8.6°, P = 0.028). The subsequent implantation of a 12 mm prosthesis, with resected PLL, resulted in a significant decrease of ROM in all motion planes compared to the 10 mm prosthesis with intact PLL (flexion/extension: 8.4°, P = 0.028; axial rotation: 3.3°, P = 0.028; lateral bending: 5.1°, P = 0.028). Compared to the intact status, the 12 mm prosthesis with resected PLL only decreased lateral bending significantly while the 10 mm prosthesis with intact PLL increased axial rotation significantly. The resection of the PLL during TDR results in a significant increase of ROM in all three principle motion planes. But it still remains unclear if this increase which is in median not more than 1° may alter the clinical results. Moreover, the destabilizing effect of PLL resection can be reversed using a higher implant. The prosthesis height seems more crucial than PLL preservation to maintain the primary stability after TDR.

Keywords

Lumbar disc replacement Range of motion Posterior longitudinal ligament Biomechanics 

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • Balkan Cakir
    • 1
  • Marcus Richter
    • 2
  • Werner Schmoelz
    • 3
  • René Schmidt
    • 4
  • Heiko Reichel
    • 1
  • Hans Joachim Wilke
    • 5
  1. 1.Department of Orthopaedic SurgeryUniversity of UlmUlmGermany
  2. 2.Spine UnitSt. Josefs HospitalWiesbadenGermany
  3. 3.Trauma Surgery and Sports MedicineMedical University of InnsbruckInnsbruckAustria
  4. 4.Department of Orthopaedic and Trauma SurgeryUniversity Medical Center MannheimMannheimGermany
  5. 5.Institute of Orthopaedic Research and BiomechanicsUniversity of UlmUlmGermany

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