Instrumented Spinal Fusion Spinal fusion is a process using bone graft to cause two opposing bony surfaces to grow together – Arthrodesis. Instrumentation utilises surgical procedures to implant devices that maintain spinal stability while facilitating the process of fusion.
The Purpose of Instrumentation Procedures are used to: Restore stability of the spine. Correct deformity, e.g. Scoliosis. Bridge space by the removal of a spinal element, e.g. intervertebral disc. Instrumentation immobilises the involved spinal levels. ↓ Patients often actually feel they are more mobile following the procedure as their pain has been reduced or eliminated.
Importance of Bony Fusion Instrumentation placed without fusion can result in hardware failure. All metal fatigues with repetitive stress. Continual stress on an implant, unsecured by a solid bone growth, can lead to screw pullout, or even fracture of the metal → complete breakdown of the construct. Consequently a solid bony fusion is crucial to the proper healing of a spinal fusion.
Bony Fusion Full bony fusion takes 6 months. Instrumentation is only designed to be functional for 9 months, after that it is ‘just there’. Factors such as osteoporosis and smoking are known to impair bone healing and reduce the success of fusion. These patients are more likely to have a pseudofusion, which can result in continued pain at the surgical site and hardware failure.
Osteopathic Considerations Presence of localised scar tissue. New junctions will establish above and below the fusion. ↓ Important not to stress these new junctional areas when articulating – never rotate specifically at those levels. ↓ Risk of pseudoarthrosis, particularly proximal to fusion, if over rotate or thrust too hard at that level. Soft tissue structures that should mobilise fused areas no longer contract/relax as the spine does not now move. With an upper Lsp fusion, often get a pseudo SIJ problem.
Treatment Strategy Examine as normal – including fused areas. Key is to optimise spinal function throughout the rest of the spine. Reduce tension in soft tissues, increase elasticity and break the pain/contracture cycle. Initiate tissue lengthening using long levers to break down adhesions. In Lsp fusions, supporting structures become very tight - particular areas to stretch and mobilise include iliocostalis, QL, gluteii, iliopsoas, iliacus, T/L & 12 th rib, thorax & pelvis. Focal manipulation can be utilised when better tissue health is established.
Sacral Fusion Spinal & pelvic mechanics change, and SIJ function alters. Unilateral SIJ fusion contralateral SIJ becomes hypermobile. Bilateral SIJ fusion early degeneration & hypermobility at L/S. Often have a flat back, fixed flexed posture – movement comes from hips. T/L & hips are inter-related through structures such as QL, psoas, thoraco-lumbar fascia. Patients tend to have reduced hip extension & they extend from T/L. Encourage extension throughout – hips, Tsp, shoulder girdles, etc. Give consideration to occupation – e.g. desk job – fixed pelvis increased mobility at junctional areas, especially T/L.
Case Presentation Pt:M, 63yrs Presentation:Ongoing low back pain, bilateral buttock & right anterior thigh pain. PMH:L4/5 & L5/S1 ALIF & percutaneous stabilisation. Osteopathic Evaluation: Restricted flexion right L3-SIJ. Restricted extension left L1-SIJ. TTT given:Mobilisation of Lsp & hips. Myofascial treatment to gluteii, LES & LEX musculature. Pre TTT ODI:22% Post TTT ODI:6%
Case Presentation Pt:F, 63yrs Presentation:Painful Tsp & Csp with retracted and painful trapezius muscle post 2nd surgery. Left with exposed spinous processes over upper Tsp. PMH:5yrs previously - T5 discectomy for disc protrusion with cord compression. 1yr previously - T4-6 posterior fusion with ligation of T4 nerve root. Osteopathic Evaluation: Restricted flexion and extension C2 – T1. Hypertonic trapezius, levator scapulae, scalenes and SCM bilaterally. TTT given:Mobilise Csp & Tsp and address soft tissue component. Pre TTT NDI:58% Post TTT NDI:32% Significant reduction in disability, reduction of medication and increase in daily activity.
Case Presentation Pt:F, 15yrs Presentation:Pain in right trapezius area. PMH:AIS - Instrumented fixation T4-T11. Chiari malformation type I (decompressed). Diagnosis:AIS (posterior correction). Osteopathic Evaluation: Restriction at L3-T4 & C4-T1 right in flexion. Restricted extension at L5-T4 & C4-T1 left. TTT given:Treatment to adjust above levels and to improve tone in trapezius and periscapular muscles. Pre TTT ODI:15% Post TTT ODI:6%