1014 BRITISH MEDICAL JOURNAL VOLUME 282 28 MARcH 1981 Chondromalacia patellae Br Med J (Clin Res Ed): first published as 10.1136/bmj.282.6269.1014 on 28 March 1981. Downloaded from

Chondromalacia patellae needs to be distinguished from six months. The residue ofpatients with apparently intolerable osteoarthritis ofthe patellofemoral joint. The former is usually discomfort may be offered chondroplasty (shaving or excision a self-limiting condition of adolescence, with a predilection of the abnormal cartilage, realignment of the patella by for girls,' affecting the articular cartilage ofthe medial patellar proximal lateral release, or transplantation, of the tibial ridge. Few ofthese patients show later overt clinical and radio- tubercle).' These operations are- by no means universally logical osteoarthritis.2 3 effective but are generally regarded as harmless. Where they Osteoarthritis is usually seen in older patients as part of seem to fail (and the criteria of failure are rather subjective), aging or perhaps after a fracture of the patella, and the dis- patellectomy or a patella resurfacing procedure may be con- order eventually extends to the rest of the joint. Since the sidered.1' Some authorities favour patellectomy12; others do causes and the natural history of the two conditions are not not.'3 Certainly the young patient with an otherwise healthy the same the treatment of each should differ, with attention knee has a better prospect of good recovery from patellectomy directed in the former to the patella alone and in the latter or resurfacing'4 than an adult with an osteoarthritic knee, but to the knee joint as a whole. even at the best the postoperative sequelae will last six months During normal function the patella is subjected to heavy and may extend to 18 months.'3 mechanical loading as it increases the moment-arm of the Resurfacing of the patella is a new procedure with some extensors ofthe knee. The act ofclimbing stairs applies a force design problems.'5 The results are only moderately good but, across the patellofemoral joint of more than three times the not surprisingly, better in patients with chondromalacia than body weight4 -around 170 kg.5 One cause of early damage to with osteoarthritis.'617 The experienced surgeon, however, the articular cartilage may be a shear stress imposed by differ- might speculate at the depressed state of the patient's psyche ing stiffness zones in the underlying bone-relative osteopenia and the reduced efficiency of the quadriceps at the end of in one area permitting the bone to collapse a little relative to a series of operations beginning with chrondroplasty, through an adjoining region.6 The patella may also be damaged in falls patella realignment, to resurfacing and finally patellectomy. or by contact with the facia in motor accidents: forces short The knee tolerates repeated surgical insults badly, and there ofthose required to fracture the bone may damage the articular may be something to be said for moving straight from con- cartilage,7 though this is likely only when the contact area servative treatment to excision of the patella, but only after between patella and femur at the time of impact is quite careful, critical, and prolonged observation of the patient. small (as occurs when the knee is at right-angles).3 The clinical diagnosis in patients complaining ofpain around Insall J. "Chondromalacia patellae": patellar malalignment syndrome. the patella needs, therefore, to take account of age, any history Orthop Clin North Am 1979;10:117-27. of trauma, and evidence of pain under circumstances where 2 Karlson S. Chondromalacia patellae. Acta Chir Scand 1940;83:347-81. 3 Smillie IS. Injuries of the knee joint. 4th ed. London: E and S Livingstone, the patellofemoral joint is subjected to stress. Examination 1970. may elicit pain under the medial articular surface of patella 4 Reilly DT, Martens M. Experimental analysis of the quadriceps muscle on pressure or on manipulating the patella against the femoral force and patello-femoral joint reaction force for various activities. Acta Orthop Scand 1972;43:126-37. condyles.8 Factors thought to provoke changes in the articular 5 Morrison JB. The mechanics of the knee joint in relation to normal walk- cartilage typical of chondromalacia are patella alta,3 patella ing. J Biomech 1970;3 :51. 6 Abernethy PJ, Townsend PR, Rose RM, Radin EL. Is chondromalacia malalignment,' and structural abnormalities in the form of an http://www.bmj.com/ patellae a separate clinical entity? 7 Bone J7oint Surg (Br) 1978;60B: extra patellar facet9 or a ridge at the proximal margin of the 205-10. articular surface ofthe medial femoral condyle.10 Some, but not 7 Repo RU, Finlay JB. Survival of articular cartilage after controlled impact. all, of these features can be identified clinically or radiologically J Bone Joint Surg (Am) 1977;59A: 1068-76. 8 Gruber MA. The conservative treatment of chondromalacia patellae. to support the diagnosis. As cartilage possesses no pain Orthop Clin North Am 1979;1O:105-15. fibres the pain is thought to arise in that area of bone no longer 9 Goodfellow J, Hungerford DS, Woods C. Patello-femoral joint mechanics and pathology. 2. Chondromalacia patellae. Jf Bone Joint Surg (Br) cushioned from stress by the damaged articular cartilage over- 1976;58B :291-9. lying it.9 10 Outerbridge RE. The aetiology of chondromalacia patellae. J Bone Joint Since chondromalacia patellae is usually a self-limiting Surg (Br) 1961 ;43B :752-7. on 1 October 2021 by guest. Protected copyright. 1 Wiles P, Andrews PS, Devas MB. Chondromalacia patellae. J Bone Joint condition, palliative conservative treatment is appropriate- Surg (Br) 1956;38B:95-113. namely, analgesics, suitable physiotherapy, and a support for 12 Bentley G. Chondromalacia patellae. 7 Bone Joint Surg (Am) 1970;52A: the patella. Strict avoidance of all sports and games, a serious 221-32. 13 Duthie HL, Hutchinson JR. The results of partial and total excision of deprivation for an adolescent, should not be necessary.' patella. J7 Bone Joint Surg (Br) 1958;40B:75-8 1. Overtreatment is always possible when pain tolerance cannot 14 Worrell RV. Some aspects of prosthetic replacement of patella. Orthopaedic Review 1976;5:39-42. be clearly assessed; adolescents frequently accept chronic or 15 Worrell RV. Prosthetic resurfacing of the patella. Clin Orthop 1979;144: recurrent discomfort badly and with impatience. 91-7. The many surgical options available are an index of thera- 16 Insall J, Tria AJ, Aglietti P. Resurfacing of the patella. J Bone Joint Surg (Am) 1980;62A:933-6. peutic chaos. Many surgeons try to avoid all surgery, and most 17 Scott RD. Prosthetic replacement of the patellofemoral joint. Orthop would certainly wish to try conservative treatment for at least Clin North Am 1979;10:129-37.