Bh. Ziran et al., KNEE FUNCTION AFTER PATELLECTOMY AND CRUCIFORM REPAIR OF THE EXTENSORMECHANISM, Clinical orthopaedics and related research, (302), 1994, pp. 138-146
When patellectomy is performed, the objectives should include restorat
ion of a moment arm, centralization of the extensor mechanism, adequat
e range of motion, and cosmesis. The cruciate repair of the extensor m
echanism described in this report has been developed to meet the afore
mentioned objectives. Eight patients with 12 patellectomies described
herein were examined with Cybex testing of the knee at a follow-up per
iod of 18 months to 20 years (mean, 56 months). A four-quadrant tissue
dissection of the patellar soft-tissue enclosure was reconstructed in
a cruciform pants-over-vest fashion, with the superomedial flap conta
ining the vastus medialis insertion on top. This ''soft-tissue'' patel
la attempts to provide a greater moment arm than simpler repairs. This
study examines whether this construct restored the torque of extensio
n while concomitantly facilitating centralization of the extensor mech
anism. Cybex testing of both knees examined both extensor and flexor f
unction with specific regard to the ratio of extensor to flexor forces
. Patients with patellectomies had few subjective complaints, with a m
ean knee score of 94 (median, 100). The extensor torque was not comple
tely restored and there was a moderate decrease in the quadriceps func
tion, both subjectively and objectively as measured by Cybex testing.
The authors also found that in patients with unilateral patellectomies
, the ratios of extension to flexion function, a parameter not yet rep
orted in the literature, were significantly different between the norm
al and patellectomized knees. The same extension to flexion ratios wer
e seen in patients with bilateral patellectomies. Because patients wit
h patellar pathology requiring patellectomy frequently have chronic an
d bilateral disease, comparative functional evaluation may be difficul
t. The use of the extension-to-flexion ratios may help in the evaluati
on of knee function after patellectomy since the flexor muscles provid
e an inherent control against which the extensor mechanism can be comp
ared.