01  What it is and why it happens

Current thinking on how these lesions develop

The capitellum is the rounded surface at the end of the humerus that articulates with the radial head. In a throwing elbow, the valgus force generated during late cocking and early acceleration pulls the medial side apart and compresses the lateral side. The radial head is driven into the capitellum with every throw. In gymnastics, cheer, and pitching-adjacent sports where the arm bears weight, the same joint absorbs repeated axial load.

The prevailing explanation combines two factors. The first is that repetitive compression and shear across the radiocapitellar joint produce microdamage in the subchondral bone faster than a growing skeleton can repair it. The second is that the capitellum has an unusually vulnerable blood supply. It is fed by end vessels entering posteriorly with minimal collateral flow, and in a skeletally immature elbow those vessels do not cross the physis. A region with high mechanical demand and marginal vascular reserve is a region where repetitive load produces a focal area of subchondral bone that does not survive.

What follows depends on that bone. If the subchondral bone reossifies, the overlying cartilage stays supported and the lesion heals. If it does not, the cartilage above it loses its foundation, the fragment separates in stages, and it can eventually detach entirely and become a loose body inside the joint.

Genetic and systemic contributions have been proposed and remain under investigation. In practice, the athletes I see with this injury share a recognizable profile: high year-round volume in a single sport during the years when the elbow is still growing.

02  Making the diagnosis

Presentation, and why these are caught late

The typical presentation is dull lateral elbow pain that worsens with throwing or with weight bearing on the arm, often accompanied by loss of terminal extension. Symptoms are frequently vague early, and the elbow feels tolerable enough that the athlete keeps playing. Catching, locking, or a sense of the joint giving way suggests a fragment that has become unstable or a loose body, and those symptoms carry a different urgency.

A lateral elbow that hurts in a young thrower deserves imaging, not a rest-and-recheck plan. Delay matters here in a way it does not with many youth sports complaints. Longer symptom duration before presentation has been associated with lower rates of healing, and radiocapitellar degenerative change is a recognized long-term consequence of lesions that are undertreated.

03  Imaging

Radiographs tell you it exists; MRI tells you what to do

Both studies are necessary, and they answer different questions.

Stability is not a formality. It is the branch point of the entire algorithm, and it is the reason I will not commit to a treatment plan on radiographs alone.

04  Nonoperative management

Which lesions actually heal with rest

For a stable lesion, activity restriction is a legitimate first-line treatment, and the honest framing of its odds is roughly a coin flip. In the largest series of stable pediatric capitellar OCD treated nonoperatively, about 54 percent healed, at an average of a little over eight months.

Several factors separate the lesions that heal from the ones that do not.

• Lesion size. A smaller lesion relative to the capitellar surface is an independent predictor of healing. Larger lesions fail more often.
• Cyst-like lesions. Their absence is the other independent predictor. In that series, lesions without cystic change healed at roughly 62 percent, while lesions with cystic change healed at about 21 percent.
• Stability grade. Lower-grade lesions healed at about twice the rate of higher-grade lesions.
• Symptom duration. Athletes who healed had presented after markedly shorter symptom duration than those who did not.
• Physeal status. Long taught as the deciding factor, and more recent evidence has been mixed. Several studies have found lesion characteristics to be the stronger predictor, with physeal status not reaching significance. An open physis remains favorable, but treating it as a guarantee of healing is a mistake I see made frequently.
• Early radiographic progress. Progression of ossification within the first three months has been shown to predict eventual union. A lesion that has not moved by three months is unlikely to be rescued by more of the same.

Nonoperative treatment means genuine rest from throwing, from weight bearing on the arm, and from anything that loads the radiocapitellar joint. It is not a reduced-volume program, and partial compliance is the most common reason a treatable lesion progresses. That is a hard message for a family in the middle of a season, and it is worth the conversation.

05  Surgical treatment

The options, and what selects among them

Surgery is indicated for unstable lesions, for loose bodies, for mechanical symptoms, and for stable lesions that have failed an adequate trial of rest. The specific procedure depends on lesion size, whether the fragment has viable subchondral bone, and where the lesion sits on the capitellum.

1. Arthroscopic debridement with marrow stimulation

   The unstable fragment and any loose bodies are removed and the base of the lesion is prepared, often with microfracture or drilling, to recruit a healing response from the underlying marrow. The technical demand is low, recovery is faster, and it works reasonably well for small lesions with an intact lateral wall. The tissue that fills the defect is fibrocartilage rather than hyaline cartilage, and for larger or lateral lesions this approach has historically been associated with less durable results in high-demand upper extremity athletes.

2. Drilling of an intact lesion

   When the cartilage surface is intact but the lesion is not healing, drilling channels into the subchondral bone restores vascular access without disturbing the cartilage above it. This can be done through the articular surface or from behind it, and it is a reasonable option in the skeletally immature athlete whose lesion has stalled.

3. Fragment fixation

   A partially detached fragment carrying viable subchondral bone can be reduced and secured with compression screws, bioabsorbable implants, or bone pegs, sometimes with bone grafting of the crater underneath. Preserving the athlete's own hyaline cartilage is the most biologically favorable outcome available, so fixation is worth pursuing when the fragment supports it. Whether it does is often a judgment made at the time of surgery.

4. Osteochondral grafting: OATS and allograft

   For large lesions, for lesions that breach the lateral wall of the capitellum, and for fragments that cannot be salvaged, the defect is reconstructed with plugs of bone and cartilage. This restores both the subchondral bone and a hyaline cartilage surface, which is what distinguishes grafting from debridement.

06  Outcomes

What the published data shows

Osteochondral grafting of the capitellum has the strongest outcomes evidence of the surgical options. A systematic review of 24 studies covering 470 patients found that 97 percent returned to sport, with individual study rates ranging from 79 to 100 percent. Patient-reported outcome scores were consistently excellent and range of motion improved reliably.

Two qualifications belong in that same conversation. Return to sport is not the same as return to the same level, and athletes should be counseled that some come back at lower performance or change positions. Lesion location also matters, with laterally located lesions associated with less favorable results than central ones.

Fresh allograft is newer in this application, and the recent evidence is encouraging. In a series of pediatric patients with unstable lesions at least 10 mm across, allograft transplantation produced low complication rates, excellent graft incorporation, high elbow function scores, and high return to sport at a minimum of two years.

Comparative data across all surgical techniques is thinner than anyone would like. A comparative review found no significant difference in the magnitude of improvement between surgical modalities for a given lesion grade, but did find that surgery outperformed nonoperative management for higher-grade lesions while low-grade lesions did similarly well either way. That is the practical case for getting the stability determination right at the beginning.

07  Recovery after grafting

The postoperative timeline

The following describes our typical course after osteochondral autograft or allograft transplantation. Debridement and fixation procedures move faster. As with any of our programs, progression is driven by imaging and functional milestones rather than by dates.

1. Week 0–1

   Splint

   You wake up in a splint that protects the elbow while the graft sits undisturbed in its earliest and most vulnerable window.

2. Weeks 1–6

   Hinged elbow brace and motion

   The splint comes off at about one week and you transition into a hinged elbow brace for roughly six weeks. Motion is restored progressively with your physical therapist while the joint surface stays protected from load.

3. ~12 weeks

   Strengthening begins

   Formal strengthening starts around three months, once early graft incorporation has had time to occur. Lower body and conditioning work continue throughout the earlier phases.

4. ~16 weeks

   Plyometrics and weight room

   Near the four-month mark we introduce plyometric work and reintegrate you into weight room activities with your team or performance staff. This is where the athlete's overall physical preparation gets rebuilt rather than merely maintained.

5. ~6 months

   Repeat MRI, then throwing

   A repeat MRI at approximately six months confirms that the graft has incorporated and the articular surface is intact. Once that is established, the interval throwing program begins. The imaging comes first, and the throwing program starts because of what it shows.

6. 9–12 months

   Return to competition

   Return to competitive play is planned for nine to twelve months, with the throwing progression built to rebuild both performance and workload capacity before full participation.

08  Common questions

Questions from athletes and parents