Proximal junctional kyphosis

Although surgical techniques pertaining to adult spinal deformity (ASD) have advanced over the last decade, proximal junctional kyphosis (PJK) is still a complication following surgery for ASD that continues to significantly challenge clinicians 1)

Proximal junctional kyphosis is defined by two criteria: a proximal junctional sagittal Cobb angle (1) ≥ 10° and (2) at least 10° greater than the preoperative measurement. PJK is multifactorial in origin and likely stems from surgical, radiographic, and patient-related risk factors. The diagnosis of PJK represents a broad spectrum of disease ranging from asymptomatic patients with recurrence of deformity to those presenting with increased pain, functional deficit, and, in the most severe cases, neurologic deficits. Recent studies have demonstrated increased pain levels in select patients with PJK. In keeping with the broad spectrum of the disease, classification schemes are needed to better describe and stratify the severity of PJK. The most severe form is proximal junctional failure. A consensus on a uniform definition of proximal junctional failure is needed to allow for more systematic study of this phenomenon 2).

Proximal junctional kyphosis (PJK) is a common postoperative complication after adult spinal deformity surgery and may manifest with neurological decline, worsening spinal deformity, and spinal instability, which warrant reoperation. Rates of PJK may be as high as 69.4% after ASD surgery.

Osteoporosis may contribute to high rates of fracture and instrumentation failure after long posterior spinal fusions, resulting in proximal junctional kyphosis and recurrent spinal deformity. As increasing numbers of elderly patients present for surgical intervention for degenerative and traumatic spinal pathologies, current and future generations of spine surgeons will increasingly be faced with the challenge of obtaining adequate fixation in osteoporotic bone 3).

A study demonstrates high inter- and intraobserver reliability of PJK measurement following instrumented fusion for ASD, independent of the presence or absence of PJF. Although slightly lower for upper thoracic than for thoracolumbar proximal endpoints, all ICCs consistently reached at least “substantial agreement” and “near perfect agreement” for most 4).

PJK was defined as a proximal junctional angle (PJA) >10° and 10° greater than the corresponding preoperative measurement. Patient demographics, operative details, standard radiographic scoliosis measurements (including PJA and assessment of PJK), and complications were analyzed.

Results: Of 184 patients, 146 (79.3%) achieved minimum 2-yr follow-up (mean = 45 mo; mean age = 67 yr; 67.8% women). PJK rates reported for the NT, TO, and TC cohorts were 60.7% (37/61), 35.7% (15/42), and 23.3% (10/43), respectively. PJK rates among TC patients were significantly lower than NT (P = .01601).

Conclusion: Junctional tethers with crosslink significantly reduced the incidence of PJK and revisions for PJK among ASD patients treated with long-segment posterior instrumented fusions who achieved minimum 2-yr follow-up 5).

Diebo BG, Shah NV, Stroud SG, Paulino CB, Schwab FJ, Lafage V. Realignment surgery in adult spinal deformity : Prevalence and risk factors for proximal junctional kyphosis. Orthopade. 2018 Apr;47(4):301-309. English. doi: 10.1007/s00132-018-3536-5. PMID: 29445843.
Kim HJ, Iyer S. Proximal Junctional Kyphosis. J Am Acad Orthop Surg. 2016 May;24(5):318-26. doi: 10.5435/JAAOS-D-14-00393. PMID: 26982965.
Goldstein CL, Brodke DS, Choma TJ. Surgical Management of Spinal Conditions in the Elderly Osteoporotic Spine. Neurosurgery. 2015 Oct;77 Suppl 4:S98-S107. doi: 10.1227/NEU.0000000000000948. PubMed PMID: 26378363.
Rastegar F, Contag A, Daniels A, Hiratzka J, Lin C, Chang J, Than K, Raslan A, Kong C, Nguyen NL, Hostin R, Kane M, Hart RA. Proximal Junctional Kyphosis: Inter- and Intraobserver Reliability of Radiographic Measurements in Adult Spinal Deformity. Spine (Phila Pa 1976). 2018 Jan 1;43(1):E40-E44. doi: 10.1097/BRS.0000000000002261. PubMed PMID: 29232355.
Rabinovich EP, Snyder MH, McClure JJ, Buell TJ, Smith JS, Shaffrey CI, Buchholz AL. Posterior Polyethylene Tethers Reduce Occurrence of Proximal Junctional Kyphosis After Multilevel Spinal Instrumentation for Adult Spinal Deformity: A Retrospective Analysis. Neurosurgery. 2021 May 10:nyab123. doi: 10.1093/neuros/nyab123. Epub ahead of print. PMID: 33971008.
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