Patellectomy is the procedure of surgical removal of the patella.
Complete removal is called 'complete patellectomy', as compared to 'partial patellectomy' where only a part of the patella bone is removed.
If you have read the section on patellar mechanics you will know that the patella lies right within the tendon of the quads muscle. To remove it, a cut is made in the tendon and the patella is freed and removed like a nut from its shell, leaving the tendon itself still functional, although inefficiently so.
Problems after patellectomy
Patellectomy is never (or should never) be undertaken lightly. Although it may be unavoidable in certain cases, the change in anatomy has significant consequences -
- Extension lag - the 'lever' mechanism of the quads muscle becomes less efficient without the patella, and it may be impossible to actively achieve the last few degrees of extension
- Increased laxity - the loss of the 'spacer' effect of the patella leaves the quads tendon lax, and prone to dislocation
- Vulnerable femoral joint surface - without the protection of the bony patella, the important cartilage covering the end of the femur is easily damaged by knocks and falls (which themselves may be more frequent because of the laxity)
- Knee replacement limitations - knee replacement is problematic after patellectomy. The relatively recent development of 'resurfacing' procedures offers some hope for relief of instability (replacement of the trochlea with an artificial metal surface).