The most common complication is irritation of the ulnar nerve, which causes numbness or tingling in the ring and small fingers. Beyond that, the list is short and the serious entries are uncommon: infection, fracture of the medial epicondyle, elbow stiffness, graft failure, and problems at the site where the graft was taken. The largest risk in practical terms is not a surgical complication at all — it is that between 10 and 20 percent of pitchers never return to their previous level of play.
Why published complication rates disagree so wildly
If you search this question you will find numbers that cannot all be right. One study of nearly 1,200 reconstructions reports an overall complication rate of 0.67 percent. A large clinical series reports 20 percent. A systematic review reports 12 percent for nerve problems alone.
Those studies are not contradicting each other. They are counting different things.
| Source | Reported rate | What it counts |
|---|---|---|
| Insurance database review, 1,191 reconstructions | 0.67% | Complications significant enough to be coded and billed |
| Systematic review, 1,518 patients | 12% nerve | Ulnar neuropathy reported at clinical follow-up, transient and permanent combined |
| Single-surgeon series, 743 athletes | 20% overall | Everything documented at follow-up; 16% minor, 4% major |
A database study counts what generated a billing code. A clinical follow-up study counts what a surgeon wrote in a chart, including numbness that resolved in three weeks and never required treatment. Neither is dishonest. But if you are trying to understand your own risk, the clinical numbers are the more useful ones, because they include the things that will actually bother you even if they eventually go away.
I would rather show you that comparison than pick whichever number flatters the operation.
Ulnar nerve problems — the most common one
The ulnar nerve runs in a groove directly behind the ligament being reconstructed. Irritating it produces numbness, tingling or a shock-like sensation into the ring and small fingers.
Pooled across 1,518 patients, about 12 percent developed ulnar neuropathy after reconstruction. A separate review of 6,671 elbows found that 14 percent developed post-operative ulnar neuritis despite having had no nerve symptoms before surgery. Most of these are transient. Fewer than 1 percent of patients require a second operation for the nerve.
The rate depends heavily on technique — roughly 4 percent with a muscle-splitting approach and the nerve left in place, versus the high teens to low twenties when the flexor-pronator mass is detached or the nerve is transposed. This is covered in detail on its own page.
Graft failure and re-tear
The reconstructed ligament can tear again, either from a new injury or from failure of the graft to mature adequately. In a recent comparison of competitive athletes, revision surgery was required in about 8 percent of reconstructions and 9 percent of repairs at midterm follow-up.
Most graft failures happen during or after the return to throwing rather than in the early post-operative period, which is why the throwing program advances on criteria rather than dates.
Infection
Uncommon. Reported at roughly 0.2 percent of reconstructions in database review. Superficial infections at the incision are treated with antibiotics; deep infection involving the graft is rare and is a more serious problem.
Call me for fever, spreading redness, warmth, or any drainage from the incision. Infection is far easier to manage early.
Fracture of the medial epicondyle
The graft is fixed through bone tunnels drilled in the medial epicondyle, and the bridge of bone between tunnels can fracture. Techniques requiring two closely spaced tunnels on each side carry a risk that the tunnels converge, collapse into one another, or break the bone between them.
This is one of the reasons I use a single bone tunnel on each side. There is no bone bridge between two tunnels to fracture. No medial epicondyle or ulnar fracture occurred in my published series.
Stiffness and loss of extension
Some loss of full extension is common early and usually resolves. Persistent stiffness is less common but real, and it is more likely when motion is started late, when the elbow is immobilized for long periods, or when the ulnar nerve has been transposed.
My protocol addresses this directly: a splint for the first 7 to 10 days and then no brace at all, with terminal extension advancing roughly 10 degrees per week from week three. Failure to achieve full extension by week eight is something I want to know about rather than watch.
Problems where the graft was taken
If your graft came from the palmaris longus tendon in the forearm, donor site problems are unusual — the incisions are small and patients rarely report lasting trouble. There is a rare but serious complication in which the median nerve is mistaken for the palmaris and harvested instead, which is discussed on the graft page along with the technique used to prevent it.
If the graft came from the gracilis in your hamstring, some patients have residual pain at the inner knee and back of the thigh that persists beyond the expected healing period. It is not common and not disabling, but it is real and it is the main trade-off of using your own tissue.
The complication nobody puts on the consent form
The risks above are the ones that appear in surgical textbooks. The one that matters most to an athlete is different.
Roughly 10 to 20 percent of pitchers never return to their previous level of play. Not because something went wrong in the operating room — because the arm, the timeline, the competition or life took a different course. Published return-to-play figures are good, with about 83 percent of Major League pitchers returning to the Major Leagues, but good is not certain.
I would rather you go into this understanding that the operation gives you a real chance at your career back, not a guarantee of it.
What my own results look like
In my published series of 36 baseball players followed for an average of more than four and a half years, one patient required revision reconstruction and returned to play, and one required removal of the humeral button. There were no medial epicondyle or ulnar fractures, and no patient developed new ulnar nerve symptoms.
Thirty-six patients is a modest series, and low numbers in a group that size do not prove a complication cannot happen. What they show is a technique performing the way its design would predict.
What reduces risk
- A muscle-splitting approach that leaves the flexor-pronator origin intact
- Leaving the ulnar nerve alone unless there were symptoms before surgery
- A single bone tunnel on each side rather than two closely spaced tunnels
- Early motion rather than prolonged immobilization
- Advancing the throwing program on criteria rather than on the calendar
- Addressing the mechanics and workload that caused the injury in the first place
Call me if any of this happens
- New, progressive or worsening numbness or tingling in the ring and small fingers
- Fever, spreading redness, warmth or drainage from the incision
- Uncontrolled pain, or a sudden increase in pain or swelling after a therapy session
- Medial elbow pain reproduced by valgus stress at any stage
- A pop, a tearing sensation, or a sudden loss of velocity during the throwing progression
- Failure to achieve full extension by week 8
The bottom line
Tommy John surgery is a reliable operation with a short list of complications, most of them uncommon and most of them manageable. Ulnar nerve irritation is the most frequent, reported at about 12 percent overall but ranging from 4 to over 20 percent depending on technique. Graft failure requiring revision runs around 8 percent. Infection and fracture are rare. Published complication rates vary enormously because studies count different things, and the honest figure to plan around is the clinical one rather than the database one. The largest real risk is not a surgical complication — it is that 10 to 20 percent of pitchers do not get all the way back.
References
- Clain JB, Vitale MA, Ahmad CS, Ruchelsman DE. Ulnar nerve complications after ulnar collateral ligament reconstruction of the elbow: a systematic review. Am J Sports Med. 2018;46(5):1263-1269.
- Cain EL, Andrews JR, Dugas JR, Wilk KE, McMichael CS, Walter JC, Riley RS, Arthur ST. Outcome of ulnar collateral ligament reconstruction of the elbow in 1281 athletes: results in 743 athletes with minimum 2-year follow-up. Am J Sports Med. 2010;38(12):2426-2434.
- Hones KM, Simcox T, Hao KA, et al. Graft choice and techniques used in elbow ulnar collateral ligament reconstruction over the last 20 years: a systematic review and meta-analysis. J Shoulder Elbow Surg. 2024;33(5):1185-1199.
- Negus MH, Guareschi ME, Wohlrab L, et al. Are suture spanning repair techniques replacing traditional Tommy John surgery? Prevalence and complication rates following ulnar collateral ligament repair or reconstruction. Orthop J Sports Med. 2026. PMID 42422464.
- Dugas JR, Froom RJ, Mussell EA, et al. Clinical outcomes of ulnar collateral ligament repair with internal brace versus ulnar collateral ligament reconstruction in competitive athletes. Am J Sports Med. 2025;53(3):525-536.
- Mirzayan R, Benvegnu N, Sidell M, Acevedo DC, DeWitt DO, Lowe N, Singh A. Functional outcomes of ulnar collateral ligament reconstruction with a novel double suspensory fixation. J Shoulder Elbow Surg. 2020;29(8):1530-1537.
- American Sports Medicine Institute. Position statement for Tommy John injuries in baseball pitchers. asmi.org.
