Introduction: Lumbar disc disease comprises of a heavy portion of the workload in spinal as well as general orthopaedic clinic.
It is well accepted that nerve root tension signs such as straight leg raise (SLR) & Lasegue’s test are sensitive at diagnosing nerve root impingement secondary to lumbar disc degeneration. In isolation, however, they lack specificity & have a poor positive predictive value (PPV). This can lead to uncertainty in clinical diagnosis.
Our study proves that a structured approach to clinical examination with cumulative nerve root tension signs (RTS) significantly increases the tests’ specificity and PPV, therefore giving clinicians more confidence in their diagnosis.
Methods: Prospective review of 1303 patients seen in one Orthopaedic consultant’s spinal clinic from 2004 until 2008. Data was collected using a standardized proforma. Pattern of pain as well as RTS (SLR, Lasegue, bowstring and crossover) were recorded and cross-referenced with subsequent MRI findings. In our dataset a positive MRI result was one in which the demonstrated disc lesion and nerve impingement corresponded with patient symptoms. Patients included were all those presenting with lower back and/or neuropathic leg pain. Patients had to be excluded from series due to incomplete datasets & missing MRI scans.
Results: N = 858. Our results showed that as we progressed from 1 RTS up to 4 RTS there was a significant increase in the PPV : 1RTS PPV = 0.333 (CI 0.25 – 0.43), 2RTS PPV = 0.78 (CI 0.69 – 0.86), 3RTS PPV 0.87 (CI 0.81 – 0.91), 4RTS PPV 0.93 (CI 0.66 – 0.99). There was also significant increases in specificity compared with 1RTS: 1RTS 0.75 (CI 0.70 – 0.8), 2RTS 0.94 (CI 0.91 – 0.96), 3RTS 0.92 (CI 0.89 – 0.95), 4RTS 0.99 (CI 0.98 – 0.99).
Discussion: This study shows that combining root tension signs as part of a structured assessment leads to a significant cumulative increase in the PPV and specificity of the diagnosis of nerve root impingement. Hence proving the importance of clinical examination. This method of sequential, cumulative RTS has not previously been documented in the literature.
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