DO RADIOGRAPHIC DETERMINANTS AFFECT THE FUNCTIONAL OUTCOME FOLLOWING C1–2 ARTHRODESIS ?

Abstract

Introduction: The literature regarding the functional outcome following C1–C2 surgeries for non-rheumatoid C1–C2 pathologies following selective arthrodesis is sparse.

Aim: To determine the long term correlation between functional outcome and radiological determinants following C1–C2 fusion for conditions other than RA.

Methods: All C1–C2 surgeris performed between 1988–2002 for non-RA etiologies were reviewed retrospectively. Selective C1–C2 fusion performed in 32 pts with a min f/u of 5 yrs formed the study group. The mean age at surgery was 57.2 yrs (r 22–84yrs). The etiologies were trauma (15), non-union (6), congenital AAD (2), C1–C2 deg. arthropathy (2), os odontoideum (2), tumours (4) and instability due to TB (1). Neurodeficit were present in 7 pts. Transarticular (TA) screws supplemented with posterior wiring was performed in 27 & posterior wiring alone in 5 pts respectively. A monocortical H-shaped autograft from iliac crest was used in all cases. There were two deaths & two pts were lost for F/U. The mean F/U was 7.8 yrs (r 5–13 yrs). Disability & pain using NDI & VAS and subjective satisfaction were recorded in all pts. We measured 1) C1/2 fixation angle, 2) Inclination of C1, 3) Anterior shift of C2 and 4) C2–7 lordosis on pre and final F/U lateral x-rays.

Results: Optimal TA screw placement was seen in 78.5% of pts. The mean improvement in NDI & VAS were from 55.4% to 19.6% and 8.4 to 1.6 respectively and was better in younger pts. Fusion was seen radiologically in 82.1% of pts at 12 mo post surgery. Segmental stability and resolution of symptoms was seen in all patients despite implant failure in 4 and incomplete fusion 5 cases respectively. Two wound dehiscences needed debridement of which one elderly pt died of MRSA sepsis 2 mo post-op. The C1–C2 segmental lordosis was significantly increased by surgery (−4.2 0 vs. −11.80; P=0.016). The subaxial cervical spine became less lordotic in initial few months post-op but eventually regained more lordosis as time progressed. The C1 inclination came into more extended position w.r.t horizontal line post-op with minimal loss of inclination subsequently. C1–C2 fixation angle and anterior shift of C2 did not have significant correlation with long term functional outcome i.e. NDI and VAS (r=0.35, p=0.17).

Conclusion: The functional outcome following C1–C2 arthrodesis is usually good despite metalwork issues and incomplete fusion in these selective group of non-rheumatoid arthritis pathologies.