SPIKING OF THE TIBIAL TUBERCLES - A RADIOLOGICAL FEATURE OF OSTEOARTHRITIS

Objective-To determine whether 'spiking' or angulation of the tibial t ubercle is associated with other radiographic markers of osteoarthriti s (OA) or pain in the knee joint, and could be taken as a reliable mar ker for early OA, in a large general population sample. Methods-A tota l of 950 women from the Chingford general population survey underwent anteroposterior extended weight bearing radiography of the knees. Angu lation of the tip of the medial and lateral tubercles, and height of t he tubercles above the tibial plateau were measured. These measures we re compared with standard radiographic indices including qualitative K ellgren and Lawrence global score, individual scores of osteophytes an d joint space narrowing, and pain score. Intraobserver and interobserv er reproducibility for assessment of spiking was tested in a subgroup of 50 films using two observers and two readings. Tibial spiking (angu lation and height) was defined for this study as the top 10th centile for the whole population. Patients with normal radiographs (Kellgren a nd Lawrence grade O) were allocated to quartile groups on the basis of spiking to define severity. Odds ratios were then calculated for the association of spiking and knee pain. Results-The majority of the meas ures of tibial spiking were highly reproducible. There was a significa nt correlation between tibial spike angulation and the presence of ost eophytes, but not joint space narrowing. The correlations for spike he ight with osteophytes and joint space narrowing were poor. There was a n association between spike angulation at the lateral tubercle and rep orted knee pain (odds ratio 1.45 (95% confidence interval 1.03 to 2.03 )) after adjustment for age, body mass index, and Kellgren and Lawrenc e score. There was no association between medial spike angulation or s pike height and pain. Among the 950 women, 683 (72%) had normal radiog raphs (Kellgren and Lawrence = O); in this group there was a similar a ssociation between pain and lateral spike angulation, but not medial s pike angulation or spike height. Conclusions-Tibial spiking is associa ted with the presence of knee osteophytes and is reproducible, but doe s not have a strong independent relationship with knee pain. In patien ts with normal radiographs there is no useful correlation between tibi al spiking and pain. Isolated tibial spiking is not a reliable sign of early knee OA, and should not routinely be reported.