A classification of disc annulus fibrosus injury and its guiding role in the repair and reconstruction of annulus fibrosus in patients with lumbar disc herniation

English Keywords:Lumbar disc herniation  Annulus fibrosus injury  Classification  Annulus fibrosus suture

English Abstract:

  【Abstract】 Objectives: To propose a classification method of intervertebral disc annulus fibrosus injury and explore its guiding values for annulus fibrosus repair and reconstruction in lumbar spine. Methods: Based on the degree and location of annulus fibrosus injury observed during endoscopic surgery, injuries were classified into types Ⅰ-Ⅳ. Type Ⅰ, no full-thickness tear in the annulus fibrosus, requiring artificial transverse incision during nucleus pulposus removal surgery; Type Ⅱ, longitudinal tear in the annulus fibrosus without defect, and which was further subdivided into ⅡA(≤1cm), ⅡB(1-1.5cm), and ⅡC(≥1.5cm) based on the tear length; Type Ⅲ, central tear in the annulus fibrosus with defect, and which was subdivided into ⅢA(≤1cm) and ⅢB(>1cm) based on the longest diameter of the defect; Type Ⅳ, tear in the annulus fibrosus near the endplate with defect, which was subdivided into ⅣA(≤1cm) and ⅣB(>1cm) based on the longest diameter of the defect. A retrospective analysis was conducted on 136 patients with single-segment lumbar intervertebral disc protrusion in our hospital. There were 75 male cases and 61 female cases, with an age of 36.5±10.3 years. According to the classification method, out of the 136 patients, 11 cases were classified as type Ⅰ, underwent conventional single-line linear suturing; Type Ⅱ cases were treated with near-endplate bone tunnel method for suturing, with type ⅡA 26 cases using linear suturing, type ⅡB 13 cases using triangular suturing, and type ⅡC 3 cases were abandoned suturing; For type ⅢA, 3 cases used triangular suturing and 3 used cross suturing, while 2 type ⅢB cases were abandoned suturing; Type Ⅳ cases also used the near-endplate bone tunnel method for suturing, with 52 type ⅣA cases using triangular suturing, 15 using parallel line suturing, 4 cases were failed in suturing, and 4 type ⅣB cases were abandoned suturing. The visual analogue scale(VAS) was used to assess the pain of the patients, and the Oswestry disability index(ODI) was used to assess the lumbar function of the patients before operation, at postoperative 3 months and final follow-up. At final follow-up, MRI was reexamined to observe the healing of the annulus fibrosus and compare the changes from the preoperative intervertebral; The MacNab criteria were used to assess the therapeutic effect. Results: All the patients successfully underwent nucleus pulposus removal and nerve root decompression surgery. There were no intraoperative complications such as nerve root injury, dural sac tear, or pseudospinal hypertension syndrome. The operation time ranged from 36min to 50min, with an average of 44.50(36.25, 50.00)min. Overall, according to the classification of annulus fibrosus injury, suturing was performed in 127 cases, with a suturing rate of 93.38%, and among which 123 cases successfully completed suturing, with a success rate of 96.85%. All 136 patients were followed up for 9-24 months, averaged 13.2 months. At final follow-up, there were 6 recurrences, including 1 type ⅡC(not sutured), 1 type ⅢA(sutured), and 4 type ⅣA(3 sutured, 1 suturing failure), with a recurrence rate of 4.412%. The intervertebral space height measured at final follow-up showed no significant change compared to the preoperative height(P>0.05), while the VAS scores for low back pain and leg pain, and ODI at 3 months postoperatively and at final follow-up were significantly improved compared to the preoperative levels(P<0.05). According to the MacNab criteria, there were 108 excellent, 14 good, 8 fair, and 6 poor in outcomes, with an excellent and good rate of 89.71%. Conclusions: The classification of lumbar disc annulus fibrosus injury is simple and clear; Adopting corresponding annulus fibrosus suturing repair surgery that is suitable for such classification can yield a high success rate of suturing and avoid unnecessary suturing, which has certain values in guiding clinical practice.