Posterior Apophyseal Ring Fracture in Adult Lumbar Disc Herniation: An 8-Year Experience in Minimally Invasive Surgical Management of 48 Cases

Abstract

Objective: Posterior apophyseal ring fracture (PARF) is an uncommon disorder that is usually accompanied by lumbar disc herniation (LDH). The aim of this study to describe the 8-year experience of performing minimally invasive treatment of PARF, giving particular attention to surgical technique and clinical outcome.

Methods: We reviewed 1,324 consecutive patients with LDH seen in our department between 2013 and 2020. Forty-eight patients (3.63%) were enrolled who were diagnosed with PARF associated with LDH and underwent transforminal endoscopic lumbar discectomy (TELD). Mean duration of the final postoperative follow-up was 5.1 years. The control group was comprised of 50 patients diagnosed with LDH without PARF at the same facility. Data on clinical outcomes were analyzed.

Results: The mean operation time in the PARF group was 105.4 minutes, which was longer than the mean operation time of the control group (83.9 minutes) (p = 0.001). Surgical complications, including dural tears (6.3%) and surgical instrument rupture (4.2%) were more common in the PARF group (p = 0.025). However, there was no significant difference in the proportion of excellent and good results and recurrence rates between the LDH patients with and those without PARF, respectively.

Conclusion: TELD is a safe and effective minimally invasive approach for the treatment of PARF. However, minimally invasive techniques may require longer operation time and steeper learning curve for inexperienced surgeons. The separation and removal of bone fragments, a key step in the procedure, requires patience and care to prevent rupture, residual surgical instruments, and leakage of cerebrospinal fluid.

Keywords: Apophysis fracture; Clinical outcome; Disc herniation; Microsurgery; Percutaneous endoscopic lumbar discectomy.

Fig. 1.

Intraoperative location and surgical procedure. (A, B) Posteroanterior and lateral radiographs obtained to determine intraoperative positioning. (C) Exposed prominent fragment. (D, E) fragments being extracted. (F) Sufficient decompression of the traversing nerve root was ensured. (G) Bone removed. (H) Nucleus pulposus removed.

Fig. 2.

Transforminal endoscopic lumbar discectomy performed on an adult male patient diagnosed with posterior apophyseal ring fracture combined with lumbar disc herniation. (A) Preoperative computed tomography on sagittal scans. (B) Postoperative computed tomography on sagittal scans. (C, D) Preoperative computed tomography on axial scans. (E, F) Postoperative computed tomography on axial scans.

Fig. 3.

Classification of posterior apophyseal ring fracture (PARF). PARF is divided into 4 types. Type I, avulsion of the arcuate fragment without causing bone defects behind the vertebral body; type II, separation of the larger central fractures, exposing the cancellous bone and causing a bond bone defect behind the vertebral body; type III, a small lateralized fracture with a round defect; and type IV, limbus fracture involving the full axial length of the posterior margin of the vertebral body.