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Arthroscopic resection of an extrasynovial ossifying chondroma of the infrapatellar fat pad: End-stage Hoffa's disease?
Arthroscopy: The Journal of Arthroscopic and Related Surgery 10(3):301-304
Published by Raven Press, Ltd. © 1994 Arthroscopy Association of North America
Case Report
Arthroscopic Resection of an Extrasynovial Ossifying Chondroma of the Infrapatellar Fat Pad: End-Stage Hoffa's Disease? Viktor E. Krebs, M.D., and Richard D. Parker, M.D.
Summary: Hoffa's disease, an obscure cause of anterior knee pain resulting from impingement and inflammation of the infrapatellar fat pad, was first reported by Albert Hoffa in 1904. Since the initial description, the clinical and pathological processes with an acute-to-chronic progression have been defined. Despite reports of eventual fibrocartilaginous transformation and ossification of the fat pad, no relation has been described between chronic impingement and the development of ossifying chondroma. We present a case of a unilateral, ossifying chondroma in the infrapatellar fat pad that resulted from chronic impingement and repetitive microtranma. This case shows the radiologic, histologic, and pathologic features of Hoffa's disease. Successful arthroscopic resection is presented. A possible relationship between impingement of the infrapatellar fat pad and the development of ossifying chondroma may exist. Key Words: HoffamFat paduImpingementmOssifying chondroma.
CASE REPORT
full extension, and flexion to 110° with anterior infrapatellar tenderness and stiffness at the extreme of joint motion. There was a hard, visible, and palpable mass anteromedial and posterior to the medial edge of the patellar tendon (Fig. 1). A patellar exam revealed normal alignment, passive patellar tilt at + 10°, lateral-medial glides into the third quadrant without apprehension, with the caudad and cephalad patellar motions diminished secondary to the palpable mass described above. No evidence of patella baja was found. Lachman's, McMurray's, and pivot shift tests were all negative. Radiographs revealed infrapatellar calcification and possible loose bodies (Fig. 2). An arthroscopy revealed no loose bodies in the joint. Multiple, dense, extrasynovial masses were visualized and probed in the anterior fat pad. Careful, systematic arthroscopic dissection and resection of the masses was carded out through superomedial, superolateral, anteromedial, and anterolateral portals. Examination of the joint revealed
A healthy 52-year-old man who presented to us with progressive stiffening and swelling of his left anterior knee over a period of 10 years. He had a history of repetitive trauma to that knee; his job required working daily on ladders, and he often banged the anterior portion of his knee into the rungs. After falling directly onto the same knee, the patient began experiencing increased anterior fullness and a shifting sensation in the joint. At that time, he sought consultation with the senior author (RDP). Physical examination of the left knee revealed a moderate effusion, minimal joint-line tenderness, From the Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A. Address correspondence and reprint requests to Richard D. Parker, M.D., The Cleveland Clinic Foundation, Department of Orthopaedic Surgery, Section of Sports Medicine-Desk A41, 9500 Euclid Avenue, Cleveland, OH 44195, U.S.A.
301
302
V. E. KREBS AND R. D. PARKER
FIG. 1. Swelling in the left infrapatellar region and a visible mass at the medial edge of the patella.
FIG. 3. Gross specimen showing a white-tan cartilaginous mass, in multiple pieces, following arthroscopic resection.
generalized grade II chondrosis of all articular surfaces, except the medial patellar facet, which had grade III changes. The tissue removed was white-tan, shiny, cartilaginous material with an osseous center. The largest mass measured 5 × 2 × 2 cm (Fig. 3). Microscopic examination showed a lobular arrangement of hyaline and fibrocartilage with prominent reactive changes, chondroid metaplasia, and cartilage enchondral ossification (Fig. 4). No atypical cells or mitotic activity was observed. Postoperative radiographs showed no evidence of calcification at 2 weeks and 1 year (Fig. 5). The patient had no further anterior knee pain and returned to work 2-3 weeks after the operation. At 1
year, he remains asymptomatic, has a left knee range of motion of 0-125 °, and has no evidence of recalcification.
2A,B
FIG. 2. a: Mercer merchant view showing a calcified mass beneath the medial edge of the left patella, b: Lateral radiograph of the knee revealing an infrapateUar calcified mass.
Arthroscopy, Vol. I0, No. 3, 1994
DISCUSSION Hoffa's disease, an eponym used by many to describe anterior knee pain, is believed to be caused by impingement of a hypertrophic infrapatellar fat pad. In 1904, Albert Hoffa, author of the 1891 Textbook of Orthopaedic Surgery, reported 20 cases and loosely described the process, pathology, and clinical presentation (1,2). Since this initial report, Hoffa's disease has remained a fairly obscure "wastebasket" diagnosis used to classify ill-defined causes
E X T R A S Y N O V I A L OSSIFYING CHONDROMA A N D HOFFA'S DISEASE
FIG. 4. Low-power magnification shows cancellous bone, chondroid metaplasia, and enchondral ossification at the osteochondral junction, surrounded by well-organized, fibrous tissue,
303
of anterior knee pain. The English literature is subjective and is based on isolated case reports and clinical observation (3-6). Recently, the pathology, clinical presentation, and treatment have been defined more objectively (7,8). The impingement process was initially reported to be secondary to minor chronic trauma to the anterior knee joint (1). Cadaveric studies support this observation, but also implicate repetitive hyperextension, genu recurvatum, and rotational sprains in the development of fat pad impingement (3,4,7,8). The presenting symptoms include pain localized to the anterior knee, minimal loss of motion, and occasional mild effusion. Physical examination may show a prominent, mildly tender infrapatellar fat pad, physiologic joint laxity, and pain at terminal extension with pressure on the fat pad (Hoffa's sign) (4,7). Two clinical phases, acute and chronic, have been proposed, with prognostic and treatment implications (8). Initially, pathogenesis was attributed to inflammation, hypertrophy, and fibrosis of the infrapatellar fat pad, which impinged between the tibia and femur during extension (1). More recent anatomic and arthroscopic studies support this theory (7,8). Histopathologic examination of the surgical specimens reveals a series of changes as inflammation progresses from the acute-to-chronic phase. (7,8). The pathologic changes correspond with the clinical phases of the disease. The acute phase is character-
5A,B
FIG. 5. a: Mercer merchant view 2 weeks postoperatively showing no residual calcification. B: Lateral radiograph at 2 weeks postoperatively showing no residual calcification.
Arthroscopy, Vol. 10, No. 3, 1994
304
V. E. KREBS A N D R. D. PARKER
ized by a normal inflammatory response; the clinical pain in this phase is caused by mechanical pressure on the edematous adipose tissue. The chronic phase results from repetitive impingement on the inflamed adipose tissue; as a consequence, the fat pad is replaced with fibroblasts and scar tissue. The clinical pain in this phase is attributed to mechanical impingement of the fibrous tissue on the articular cartilage, on the soft tissue capsule, or both (7,8). Histologic examination of the chronic phase further shows a regular arrangement of dense fibrous tissue with areas of cartilaginous transformation (7). Ossification of the cartilaginous islands in the fat pad has been found in patients with Hoffa's disease (7,8), but no radiographs have been published. The literature contains several case reports in which patients have presented with clinical signs, history, symptoms, and radiographic findings similar to those of our patient (9,10). The anterior knee masses in these cases have been identified as paraarticular chondromas and have pathologic features similar to those in our case. The chondromas all were described as extrasynovial fibrous bodies with histologic chondroid metaplasia and areas of enchondral ossification (9-11). Because of the similarities between our case, the cases of para-articular chondromas, and the descriptions of Hoffa's disease, we believe they may be related. Although we have no direct evidence that chronic impingement and repetitive microtrauma of the infrapatellar fat
Arthroscopy, Vol. 10, No. 3, 1994
pad results in the development of an extra-articular ossifying chondroma, our case leads us to conclude that this may occur, and thus, such a chondroma may represent the end stage of Hoffa's disease. Acknowledgment: We would like to thank Renee Hendershott and Cassandra Talerico, and acknowledge their work in the preparation of this article. REFERENCES 1. Hoffa A. The influence of the adipose tissue with regard to the pathology of the knee joint. JAMA 1904;42:795. 2. Thomann KD. A modern textbook is 100 years old: Albert Hoffa and the Textbook of Orthopaedic Surgery. Z Orthop 1992;130:339--44. 3. Smillie IS. Injuries of the knee joint. London: Churchill Livingstone, 1970:351-3. 4. Smillie IS. Diseases of the knee joint. London: Churchill Livingstone, 1980:161-71. 5. Helfet AJ. Disorders of the knee. Philadelphia: J.B. Lippincott, 1982:145-56,378. 6. De Marchais J, Gagnon P. Hoffa's disease proceedings. J Bone Joint Surg [Br] 1974;56:586. 7. Metheny JA, Mayor MB. Hoffa's disease: chronic impingement of the infrapatellar fat pad. Am J Knee Surg 1988;t: 134-9. 8. Magi M, Branca A, Bucca C, Langerame V. Hoffa disease. Ital J Orthop Traumatol 1991;17:211-6. 9. Moswer JF, Kettelkamp DB, Campbell CJ. Intracapsular or para-articular chondroma: a report of three cases. J Bone Joint Surg [Am] 1966;48:1561-9. 10. Milgram JW, Dunn EJ. Para-articular chondromas and osteochondromas: a report of three cases. Clin Orthop 1980; 148:147-51. 11. B6stman O, Karaharju E, Heikkonen L, Howmstr6m T. Extraskeletal ossifying chondroma in the knee: a case report. Acta Orthop Scand 1985;56:87-9.
Published by Raven Press, Ltd. © 1994 Arthroscopy Association of North America
Case Report
Arthroscopic Resection of an Extrasynovial Ossifying Chondroma of the Infrapatellar Fat Pad: End-Stage Hoffa's Disease? Viktor E. Krebs, M.D., and Richard D. Parker, M.D.
Summary: Hoffa's disease, an obscure cause of anterior knee pain resulting from impingement and inflammation of the infrapatellar fat pad, was first reported by Albert Hoffa in 1904. Since the initial description, the clinical and pathological processes with an acute-to-chronic progression have been defined. Despite reports of eventual fibrocartilaginous transformation and ossification of the fat pad, no relation has been described between chronic impingement and the development of ossifying chondroma. We present a case of a unilateral, ossifying chondroma in the infrapatellar fat pad that resulted from chronic impingement and repetitive microtranma. This case shows the radiologic, histologic, and pathologic features of Hoffa's disease. Successful arthroscopic resection is presented. A possible relationship between impingement of the infrapatellar fat pad and the development of ossifying chondroma may exist. Key Words: HoffamFat paduImpingementmOssifying chondroma.
CASE REPORT
full extension, and flexion to 110° with anterior infrapatellar tenderness and stiffness at the extreme of joint motion. There was a hard, visible, and palpable mass anteromedial and posterior to the medial edge of the patellar tendon (Fig. 1). A patellar exam revealed normal alignment, passive patellar tilt at + 10°, lateral-medial glides into the third quadrant without apprehension, with the caudad and cephalad patellar motions diminished secondary to the palpable mass described above. No evidence of patella baja was found. Lachman's, McMurray's, and pivot shift tests were all negative. Radiographs revealed infrapatellar calcification and possible loose bodies (Fig. 2). An arthroscopy revealed no loose bodies in the joint. Multiple, dense, extrasynovial masses were visualized and probed in the anterior fat pad. Careful, systematic arthroscopic dissection and resection of the masses was carded out through superomedial, superolateral, anteromedial, and anterolateral portals. Examination of the joint revealed
A healthy 52-year-old man who presented to us with progressive stiffening and swelling of his left anterior knee over a period of 10 years. He had a history of repetitive trauma to that knee; his job required working daily on ladders, and he often banged the anterior portion of his knee into the rungs. After falling directly onto the same knee, the patient began experiencing increased anterior fullness and a shifting sensation in the joint. At that time, he sought consultation with the senior author (RDP). Physical examination of the left knee revealed a moderate effusion, minimal joint-line tenderness, From the Cleveland Clinic Foundation, Cleveland, Ohio, U.S.A. Address correspondence and reprint requests to Richard D. Parker, M.D., The Cleveland Clinic Foundation, Department of Orthopaedic Surgery, Section of Sports Medicine-Desk A41, 9500 Euclid Avenue, Cleveland, OH 44195, U.S.A.
301
302
V. E. KREBS AND R. D. PARKER
FIG. 1. Swelling in the left infrapatellar region and a visible mass at the medial edge of the patella.
FIG. 3. Gross specimen showing a white-tan cartilaginous mass, in multiple pieces, following arthroscopic resection.
generalized grade II chondrosis of all articular surfaces, except the medial patellar facet, which had grade III changes. The tissue removed was white-tan, shiny, cartilaginous material with an osseous center. The largest mass measured 5 × 2 × 2 cm (Fig. 3). Microscopic examination showed a lobular arrangement of hyaline and fibrocartilage with prominent reactive changes, chondroid metaplasia, and cartilage enchondral ossification (Fig. 4). No atypical cells or mitotic activity was observed. Postoperative radiographs showed no evidence of calcification at 2 weeks and 1 year (Fig. 5). The patient had no further anterior knee pain and returned to work 2-3 weeks after the operation. At 1
year, he remains asymptomatic, has a left knee range of motion of 0-125 °, and has no evidence of recalcification.
2A,B
FIG. 2. a: Mercer merchant view showing a calcified mass beneath the medial edge of the left patella, b: Lateral radiograph of the knee revealing an infrapateUar calcified mass.
Arthroscopy, Vol. I0, No. 3, 1994
DISCUSSION Hoffa's disease, an eponym used by many to describe anterior knee pain, is believed to be caused by impingement of a hypertrophic infrapatellar fat pad. In 1904, Albert Hoffa, author of the 1891 Textbook of Orthopaedic Surgery, reported 20 cases and loosely described the process, pathology, and clinical presentation (1,2). Since this initial report, Hoffa's disease has remained a fairly obscure "wastebasket" diagnosis used to classify ill-defined causes
E X T R A S Y N O V I A L OSSIFYING CHONDROMA A N D HOFFA'S DISEASE
FIG. 4. Low-power magnification shows cancellous bone, chondroid metaplasia, and enchondral ossification at the osteochondral junction, surrounded by well-organized, fibrous tissue,
303
of anterior knee pain. The English literature is subjective and is based on isolated case reports and clinical observation (3-6). Recently, the pathology, clinical presentation, and treatment have been defined more objectively (7,8). The impingement process was initially reported to be secondary to minor chronic trauma to the anterior knee joint (1). Cadaveric studies support this observation, but also implicate repetitive hyperextension, genu recurvatum, and rotational sprains in the development of fat pad impingement (3,4,7,8). The presenting symptoms include pain localized to the anterior knee, minimal loss of motion, and occasional mild effusion. Physical examination may show a prominent, mildly tender infrapatellar fat pad, physiologic joint laxity, and pain at terminal extension with pressure on the fat pad (Hoffa's sign) (4,7). Two clinical phases, acute and chronic, have been proposed, with prognostic and treatment implications (8). Initially, pathogenesis was attributed to inflammation, hypertrophy, and fibrosis of the infrapatellar fat pad, which impinged between the tibia and femur during extension (1). More recent anatomic and arthroscopic studies support this theory (7,8). Histopathologic examination of the surgical specimens reveals a series of changes as inflammation progresses from the acute-to-chronic phase. (7,8). The pathologic changes correspond with the clinical phases of the disease. The acute phase is character-
5A,B
FIG. 5. a: Mercer merchant view 2 weeks postoperatively showing no residual calcification. B: Lateral radiograph at 2 weeks postoperatively showing no residual calcification.
Arthroscopy, Vol. 10, No. 3, 1994
304
V. E. KREBS A N D R. D. PARKER
ized by a normal inflammatory response; the clinical pain in this phase is caused by mechanical pressure on the edematous adipose tissue. The chronic phase results from repetitive impingement on the inflamed adipose tissue; as a consequence, the fat pad is replaced with fibroblasts and scar tissue. The clinical pain in this phase is attributed to mechanical impingement of the fibrous tissue on the articular cartilage, on the soft tissue capsule, or both (7,8). Histologic examination of the chronic phase further shows a regular arrangement of dense fibrous tissue with areas of cartilaginous transformation (7). Ossification of the cartilaginous islands in the fat pad has been found in patients with Hoffa's disease (7,8), but no radiographs have been published. The literature contains several case reports in which patients have presented with clinical signs, history, symptoms, and radiographic findings similar to those of our patient (9,10). The anterior knee masses in these cases have been identified as paraarticular chondromas and have pathologic features similar to those in our case. The chondromas all were described as extrasynovial fibrous bodies with histologic chondroid metaplasia and areas of enchondral ossification (9-11). Because of the similarities between our case, the cases of para-articular chondromas, and the descriptions of Hoffa's disease, we believe they may be related. Although we have no direct evidence that chronic impingement and repetitive microtrauma of the infrapatellar fat
Arthroscopy, Vol. 10, No. 3, 1994
pad results in the development of an extra-articular ossifying chondroma, our case leads us to conclude that this may occur, and thus, such a chondroma may represent the end stage of Hoffa's disease. Acknowledgment: We would like to thank Renee Hendershott and Cassandra Talerico, and acknowledge their work in the preparation of this article. REFERENCES 1. Hoffa A. The influence of the adipose tissue with regard to the pathology of the knee joint. JAMA 1904;42:795. 2. Thomann KD. A modern textbook is 100 years old: Albert Hoffa and the Textbook of Orthopaedic Surgery. Z Orthop 1992;130:339--44. 3. Smillie IS. Injuries of the knee joint. London: Churchill Livingstone, 1970:351-3. 4. Smillie IS. Diseases of the knee joint. London: Churchill Livingstone, 1980:161-71. 5. Helfet AJ. Disorders of the knee. Philadelphia: J.B. Lippincott, 1982:145-56,378. 6. De Marchais J, Gagnon P. Hoffa's disease proceedings. J Bone Joint Surg [Br] 1974;56:586. 7. Metheny JA, Mayor MB. Hoffa's disease: chronic impingement of the infrapatellar fat pad. Am J Knee Surg 1988;t: 134-9. 8. Magi M, Branca A, Bucca C, Langerame V. Hoffa disease. Ital J Orthop Traumatol 1991;17:211-6. 9. Moswer JF, Kettelkamp DB, Campbell CJ. Intracapsular or para-articular chondroma: a report of three cases. J Bone Joint Surg [Am] 1966;48:1561-9. 10. Milgram JW, Dunn EJ. Para-articular chondromas and osteochondromas: a report of three cases. Clin Orthop 1980; 148:147-51. 11. B6stman O, Karaharju E, Heikkonen L, Howmstr6m T. Extraskeletal ossifying chondroma in the knee: a case report. Acta Orthop Scand 1985;56:87-9.