Objective

Our aim is to assess the use of the cervical nerve root block (CNRB) in the treatment of radicular pain associated with degenerative cervical spine disease and its potential to limit the need for surgical intervention.

Retrospective analysis of radiology reports of conventional MRI in 100 patients with definite spinal stenosis to determine the incidence of reported “foraminal stenosis”.

Prospective study of MRI including T2 coronal and T2 STIR coronal sequences in 57 patients with suspected stenosis. Three surgeons and one radiologist independently compared the diagnoses on conventional and coronal scans.

Patients with suspected spinal stenosis undergoing MRI.

Incidence of “foraminal stenosis” on radiologists' reports.

Diagnoses obtained by different scanning methods.

Retrospective analysis: “foraminal stenosis” called by radiologists in 46% using conventional axial and sagittal sequences.

Prospective study - 57 patients: conventional sequences diagnosed lateral recess stenosis well but also suggested foraminal stenosis in 33%. However, coronal sequences clearly showed no foraminal nerve compression.

In degenerative spondylolisthesis conventional scans suggested foraminal stenosis in 8 of 11 cases. Coronals showed no foraminal stenosis.

Excellent correlation was found in normal spines and in disc herniation. In far lateral disc herniation and isthmic spondylolisthesis, true foraminal stenosis was confirmed by conventional and coronal imaging.

Additional coronal MRI sequences prove that foraminal stenosis is over-diagnosed and is rare in spinal stenosis, but true foraminal nerve compression occurs in isthmic spondylolisthesis and far lateral disc herniation.

Over 80% of patients are satisfied following total knee arthroplasty (TKA). Female gender was one of the factors found to be a predictor of poorer satisfaction. The landmarks commonly used to achieve correct rotation of the femoral component are the posterior condylar axis, the transepicondylar axes (TEA) & the anteroposterior axis (Whiteside’s line) of the distal femur. The design features of most conventional jig based TKA instrumentation assumes a constant relationship of 3 degrees external rotation between the posterior condylar axis & the epicondylar axis. However during TKA using computer assisted navigation, we observe that these rotational landmarks do not have a constant relationship & there is wide variation among the arthritic population & between the male & female rotational profile. We hypothesise no consistent relationship between the posterior condylar axis, the TEA & the anteroposterior axis of the distal femur.

125 Computerised Tomography (CT) scans of the knee were performed using a 3D helical CT scanner in subjects who did not have any pre-existing clinical & radiological evidence of knee arthritis. CT slices 3 mm in thickness were obtained over the distal femur from the level of the proximal pole of the patella. Standard protocols were established for identifying the bony landmarks & taking measurements. The posterior condylar axis, the TEA & the anteroposterior axis were constructed. The condylar twist angle (CTA), the posterior condy-lar angle (PCA) & the angles made by the TEA & the line perpendicular to the anteroposterior axis were then measured using the PACSWEB digital measurement tools. The data was analysed to determine the consistency of the angular relationship between the reference axes using the STATA data analysis & statistical software. Linear regression was used to investigate any differences in the angle measurements between genders.

125 CT scans of the knee were performed in 111 patients (60 males [65 knees] & 51 females [60 knees]). The mean age was 45 years (SD, 15 years). The results showed no significant difference between the rotational axes of the distal femur between men & women (CTA male(SD): female(SD): 5.9(1.6): 6.3(2.0) [p=0.317], PCA male(SD): female(SD): 2.3(1.5): 2.5(1.9) [p=0.648]). The results also showed it would be inappropriate to assume a constant relationship of 3 degress external rotation between the posterior condylar axis & the epicondylar axes (PCA mean (SD) 2.39(1.70) [p< 0.001], CTA mean (SD) 6.11(1.81) [p< 0.001]).

Our study suggests no significant difference between the rotational reference axes of the distal femur between men & women. Furthermore, most jig-based systems result in 3 degress external rotation of the femoral component. Our results show this is not consistent & may be responsible for the pain in 20% of patients post TKA because of abnormal patellar tracking.

Restoration of the position of the prosthetic joint line to the same level as the natural joint line, is a challenging problem in primary and revision knee arthroplasty and there is no reliable method for achieving this objective. We hypothesise that there is a constant ratio between the inter-epicondylar distance and the distance from this interepicondylar line to the joint line.

We analysed one hundred Computerised Tomography (CT) scans of the knee in the non arthritic population to study this relationship. The inter-epicondylar distance and the perpendicular distance from this inter-epicondylar line to the joint line was measured using both the clinical and surgical epicondylar axes for each knee as described in previous literature.

The results showed that using the clinical epicondylar axis the inter-epicondylar distance was 3 times the perpendicular distance from the inter-epicondylar line to the joint line (the median and mean ratio 3.0, Standard Deviation ±0.21). Using the surgical epicondylar axis the inter-epicondylar distance was 3.3 times the perpendicular distance from the inter-epicondylar line to the joint line (the median and mean ratio 3.3, SD ±0.25).

Landmarks such as inferior pole of patella or fibular head have been used to estimate the joint line position, but these methods have been shown to be unreliable. Our method will give an accurate estimate of the position of the joint line from the clinical epicondylar axis distance. This distance is easily calculated when using Computer Navigation for the surgery in both the primary and revision setting and the modern software programmes for Computer Assisted TKR should be modified accordingly. We conclude that the position of the joint line from the inter-epicondylar line is one-third of the inter-epicondylar distance which is valuable especially when there is significant bone loss at the tibio-femoral articulation.