Osteochondritis dissecans, an idiopathic condition involving the articular surface of a joint, can affect any number of joints within the body. First described in the late 19th century by Sir James Paget,1 osteochondritis dissecans earned its name from Franz König,2 who felt it was attributable to dissecting inflammation of the joint cartilage. During the past 120 years, many theories have been proposed for the etiology of osteochondritis dissecans; however, the precise etiology of this condition is yet to be determined.
Familial cases of osteochondritis dissecans are rare, yet evidence exists to support a genetic link. Lee et al3 describes bilateral femoral head osteochondritis dissecans lesions involving a father, his son, and his nephew. Mei-Dan et al4 and Kenniston et al5 presented cases of osteochondritis dissecans lesions in dizygotic, or fraternal, and monozygotic, or identical, twins, respectively. Most relevant report to the current articles is the case by Onoda et al,6 which describes identical twins with osteochondritis dissecans lesions, both of which achieved successful union after surgical intervention for unstable osteochondritis dissecans lesions. These reports give support to theories of a genetic predisposition, which has yet to be completely understood or identified, but coincide with the findings of our case reports.
This article describes osteochondritis dissecans lesions of the femoral trochlea in identical twins. The brothers presented with similar clinical symptoms within 1 year of each other, and neither brother had a traumatic event preceding the onset of his knee pain. Both were active in high school athletics. The brothers underwent the same surgical procedure and rehabilitation and were able to return to competitive sport. Identical twins with osteochondritis dissecans lesions have been described previously5,6; however, the current cases are interesting and unique because the osteochondritis dissecans lesions occurred in the same location of the left knee and became symptomatic at approximately the same time.
In December 2010, a 15-year-old boy presented to his pediatrician with diffuse left knee pain and intermittent swelling that had been present for at least 1 year. No mechanical symptoms were present, and he reported no inciting injury. After failing to improve with conservative treatment of nonsteroidal anti-inflammatory drugs and rest from athletic activity, he was referred to an orthopedist. Orthopedic examination demonstrated full range of motion, no mechanical symptoms, mild joint effusion, and pain localized anteriorly near the patellofemoral joint that worsened with active extension.
Magnetic resonance imaging revealed an osteochondral lesion of the lateral trochlea. The lesion, within the concavity of the trochlea, measured 16×20 mm with a depth of 6 mm with fluid signal beneath the fragment, indicating instability (Figure 1). Loose body removal, lateral release, osteochondral autograft transfer, and tibial tubercle anteromedialization were performed (Figures 2A, B).
Figure 1: T2-weighted selected axial (A) and sagittal (B) magnetic resonance images of patient 1 showing the osteochondral lesion of the lateral femoral trochlea with signal identifiable posterior to the lesion.
Figure 2: Patient 1. Intraoperative photographs showing the osteochondritis dissecans lesion prepared for the osteochondral autograft transfer procedure (A) and after osteochondral plug transfer (B). Intraoperative view of the healing osteochondral plugs 2 months after the index procedure showing smooth cartilaginous surfaces with filling in of defects between plugs (C).
Two months postoperatively, the patient exhibited mechanical symptoms in the operative knee. Magnetic resonance imaging indicated intra-articular loose bodies present. During arthroscopic removal of the loose bodies, an inspection of the previous osteochondral autograft transfer showed stable and smooth incorporation of the transplanted osteochondral plugs (Figure 2C). Postoperative rehabilitation was followed, and at 6 months he was cleared to return to competitive sports. The patient has had no further issues to date.
Approximately 1 year after his identical twin brother’s initial visit, the patient presented with a 4-month history of diffuse knee pain that worsened with activity. Examination demonstrated full active range of motion, positive patellar grind test, and no effusion.
Magnetic resonance imaging revealed a 22×10-mm osteochondral lesion with a depth of 8 mm on the left lateral trochlea (Figure 3). Fluid behind the fragment indicated an unstable lesion. Loose body removal, osteochondral autograft transfer, tibial tubercle transfer, and lateral release were performed (Figure 4). The patient followed a postoperative protocol similar to that of his brother A. He progressed well, with full return to competitive sports at 6 months postoperatively.
Figure 3: T2-weighted axial (A) and sagittal (B) magnetic resonance images of patient 2 showing an osteochondral lesion of the lateral femoral trochlea with signal identifiable posterior to the lesion.
Figure 4: Patient 2. Intraoperative photographs showing the full-thickness osteochondral lesion in situ with exposed bony base (A), the osteochondritis dissecans lesion being prepared and sized for the osteochondral autograft transfer procedure (B), and the osteochondritis dissecans lesion after osteochondral plug transfer (C).
Osteochondritis dissecans is a condition of unknown etiology. It most commonly affects the knee and is a source of pain in adults and juveniles. In their cumulative review of knowledge on this disorder, Edmonds and Polousky7 recognized osteochondritis dissecans as a lesion affecting subchondral bone with varying degrees of osseous resorption and collapse. The overlying articular surface appears to undergo softening, which then progresses to separation of the articular piece and subsequently results in osteochondral loose bodies.8 Despite various suggested etiologies, such as trauma (repetitive microtrauma vs acute macrotrauma), inflammation, constitutional factors including abnormal collagen formation, and vascular abnormalities, no clear cause exists for this disorder.7,9
The appearance of osteochondritis dissecans lesions in identical twin brothers without an inciting event leads to a discussion regarding a potential genetic basis for this disorder. Both brothers were competitive high school athletes, which could provide some support to the hypothesis of repetitive trauma injury that may be more prominent in athletes.7 The European Pediatric Orthopaedic Society reported that 55% of patients with osteochondritis dissecans lesions were regularly involved in sports or performing strenuous athletic activity.10
Even with these findings potentially supporting a repetitive microtrauma etiology, it seems more than coincidence that identical twins would develop similar lesions at the same location within their knee around the same time in life. This is reasonable evidence to suggest that the etiology of osteochondritis dissecans has a genetic component. Stattin et al11 reported a missense mutation resulting in abnormal C-type lectin, which normally mediates interactions of proteins and the cartilage extracellular matrix. Five generations of a family were studied, and an autosomal-dominant inheritance pattern for osteochondritis dissecans was revealed.11 Other studies have also reported an autosomal-dominant familial inheritance pattern for osteochondritis dissecans.12,13 The current case report provides further evidence to support a genetic basis for osteochondritis dissecans.
This article described identical twins, both highly active in competitive sports, with essentially identical trochlear lesions. Despite this case report and others denoting a familial incidence, it seems likely that this disorder may be multifactorial. Identical twins with similar histories, lesion locations, and timing are highly suggestive of a genetic component. However, the true etiology of this disorder remains controversial. Contributing variables, such as athletic endeavors with presumed repetitive stress and microtrauma, need to be considered. Although this case report does not identify the true etiology of osteochondritis dissecans, it lends substantive support to a genetic link. Clinicians should be aware of a potential genetic predilection for osteochondritis dissecans, in addition to other potential contributory factors, when treating early joint pain in siblings of osteochondritis dissecans patients so that they can facilitate prompt examination and timely diagnosis, which may potentially alter treatment.
- Kocher MS, Tucker R, Ganley TJ, Flynn JM. Management of osteochondritis dissecans of the knee: current concepts review. Am J Sports Med. 2006; 34(7):1181–1191. doi:10.1177/0363546506290127 [CrossRef]
- König F. Uber freie Korper in den gelenken. Deutsche Zeitschrift für Chirurgie. 1888; 27(1–2):90–109. doi:10.1007/BF02792135 [CrossRef]
- Lee MC, Kelly DM, Sucato DJ, Herring JA. Familial bilateral osteochondritis dissecans of the femoral head. A case series. J Bone Joint Surg Am. 2009; 91(11):2700–2707. doi:10.2106/JBJS.H.00924 [CrossRef]
- Mei-Dan O, Mann G, Steinbacher G, Cugat RB, Alvarez PD. Bilateral osteochondritis dissecans of the knees in monozygotic twins: the genetic factor and review of the etiology. Am J Orthop. 2009; 38(9):E152–E155.
- Kenniston JA, Beredjiklian PK, Bozentka DJ. Osteochondritis dissecans of the capitellum in fraternal twins: case report. J Hand Surg Am. 2008; 33(8):1380–1383. doi:10.1016/j.jhsa.2008.05.008 [CrossRef]
- Onoda S, Sugita T, Aizawa T, Ohnuma M, Takahashi A. Osteochondritis dissecans of the knee in identical twins: a report of two cases. J Orthop Surg (Hong Kong). 2012; 20(1):108–110.
- Edmonds EW, Polousky J. A review of knowledge in osteochondritis dissecans: 123 years of minimal evolution from König to the ROCK study group. Clin Orthop Relat Res. 2013; 471(4):1118–1126. doi:10.1007/s11999-012-2290-y [CrossRef]
- Mason JB, Fehring TK. Management of extra-articular deformity in total knee arthroplasty with navigation. In: Scott WN, ed. Insall & Scott Surgery of the Knee. 5th ed. Philadelphia, PA: Churchill Livingstone; 2011:1234.
- Jackson GC, Marcus-Soekarman D, Stolte-Dijkstra I, Verrips A, Taylor JA, Briggs MD. Type IX collagen gene mutations can result in multiple epiphyseal dysplasia that is associated with osteochondritis dissecans and a mild myopathy. Am J Med Genet A. 2010; 152(4):863–869.
- Hefti F, Beguiristain J, Krauspe R, et al. Osteochondritis dissecans: a multicenter study of the European Pediatric Orthopedic Society. J Pediatr Orthop B. 1999; 8(4):231–245.
- Stattin EL, Wiklund F, Lindblom K, et al. A missense mutation in the aggrecan C-type lectin domain disrupts extracellular matrix interactions and causes dominant familial osteochondritis dissecans. Am J Hum Genet. 2010; 86(2):126–137. doi:10.1016/j.ajhg.2009.12.018 [CrossRef]
- Mubarak SJ, Carroll NC. Familial osteochondritis dissecans of the knee. Clin Orthop Relat Res. 1979; (140):131–136.
- Phillips HO, Grubb SA. Familial multiple osteochondritis dissecans. Report of a kindred. J Bone Joint Surg Am. 1985; 67(1):155–156.