FCU Tendinitis
Jacksonville, FL
Volar ulnar wrist pain near the pisiform that worsens with gripping and wrist flexion — that's the FCU tendon, and in Dr. Graham's experience it's among the most responsive of all the wrist tendinopathies to conservative treatment. Most patients never need surgery. Brace, PT, and one well-placed injection resolve the vast majority of cases.
- Volar ulnar wrist pain — palm side, pinky side
- Tenderness at or near the pisiform on palpation
- Worse with resisted wrist flexion and ulnar deviation
- Pain with gripping and carrying under load
- No numbness (numbness points toward ulnar nerve)
- Surgery rarely necessary — most cases resolve conservatively
FCU tendinitis is volar-ulnar pain — palm side, pinky side, at the pisiform. ECU tendinitis is dorsal-ulnar — the back of the wrist, pinky side. Same general region, opposite sides. The distinction is made by palpation and provocation testing in under two minutes.
Understanding the Condition
The FCU Tendon at
the Pisiform
The flexor carpi ulnaris (FCU) is the primary wrist flexor and ulnar deviator on the volar-ulnar side of the forearm — the counterpart of the ECR on the radial side. Its tendon travels down the medial forearm and inserts onto the pisiform, a small sesamoid-like carpal bone nestled in the hypothenar eminence at the volar-ulnar wrist. From the pisiform, force is transmitted through the pisohamate and pisometacarpal ligaments to the hamate and fifth metacarpal.
Unlike the FCR — which passes through its own fibro-osseous tunnel at the trapezium — the FCU inserts directly onto the pisiform without a dedicated tunnel. This makes the anatomy simpler, and it is one reason FCU tendinitis generally responds better to conservative treatment: there is no tight fibro-osseous channel amplifying the compressive forces on a degenerated tendon. Inflammation and swelling around the FCU insertion have somewhere to go.
FCU tendinopathy develops from the same angiofibroblastic degeneration seen in the other overuse tendinopathies — repeated wrist flexion and ulnar deviation loading the insertion until the normal collagen architecture breaks down. Athletes who perform repetitive gripping under load (baseball, golf, racquet sports) and manual workers who carry or grip with sustained wrist flexion are the typical patient populations. The degeneration may occur at the pisiform insertion itself, or slightly more proximally along the tendon, which is why MRI — when ordered — guides the surgical target.
FCU tendinitis is among the most straightforward of the wrist tendinopathies to treat. The injection is well-tolerated, the anatomy is accessible, and the tendon responds reliably to the combination of immobilization and one targeted cortisone injection. Surgery, when it is eventually needed, is a clean debridement at the site of degeneration with a fast recovery.
The FCU tendon (orange) inserts onto the pisiform, with force continuing via the pisohamate ligament to the hamate. The red oval marks the degeneration zone at or near the insertion — wherever MRI shows pathology is where debridement is targeted.
The purple dashed line traces the ulnar nerve, which runs immediately adjacent through Guyon's canal at the wrist. Dr. Graham assesses for nerve involvement at both Guyon's canal and the cubital tunnel at every FCU evaluation.
Important Assessment
Ulnar Nerve Evaluation — Always Included
The FCU and the ulnar nerve are neighbors throughout the forearm and wrist. Dr. Graham assesses for nerve compression at both relevant sites on every FCU tendinitis evaluation — because when both are present, both need to be addressed.
Cubital Tunnel Syndrome
The ulnar nerve passes through the cubital tunnel at the medial elbow — a channel formed between the medial epicondyle and the olecranon, beneath the two heads of the FCU. Because the FCU's proximal origin is at the cubital tunnel, FCU tendinopathy and cubital tunnel syndrome can coexist and may share common provocative loading patterns. Dr. Graham evaluates for cubital tunnel symptoms — numbness and tingling in the ring and small fingers, weakness of hand intrinsics, elbow-level medial tenderness — at every FCU presentation. When cubital tunnel is confirmed alongside FCU tendinitis, both are addressed in the overall management plan.
Guyon's Canal Compression
At the wrist, the ulnar nerve passes through Guyon's canal — a fibro-osseous channel formed by the pisiform and hamate, immediately adjacent to the FCU insertion. When FCU tendinopathy produces swelling and inflammation at the pisiform, this swelling can encroach on Guyon's canal and compress the ulnar nerve at the wrist level. This produces numbness and tingling in the ring and small fingers — the same distribution as cubital tunnel — but at a different anatomical level. Distinguishing the two is important for treatment planning, and both sites are systematically examined at every FCU evaluation.
Scroll the table sideways to see all columns
| Feature | FCU Tendinitis | ECU Tendinitis | Cubital Tunnel / Guyon's Canal |
|---|---|---|---|
| Side of wrist | Volar (palm side), ulnar | Dorsal (back side), ulnar | Ulnar — elbow or wrist level |
| Primary symptom | Focal pain at pisiform with flexion/grip | Dorsal ulnar pain with extension/ulnar deviation | Numbness and tingling, ring and small fingers |
| Numbness | No | No | Yes — defining symptom |
| Provocative test | Resisted wrist flexion, FCU/pisiform palpation | Resisted extension, ECU groove palpation | Tinel's at elbow or wrist, elbow flexion test |
| Injection approach | FCU sheath at pisiform — one injection | ECU sheath at sixth compartment — one injection | Not injected — NCS needed; may require surgery |
Recognizing FCU Tendinitis
Symptoms
The presentation is focused and predictable — volar ulnar wrist pain with flexion and grip, tenderness over the pisiform, no numbness.
Volar Ulnar Wrist Pain
The pain is on the palm side of the wrist, on the pinky side — at or near the pisiform, the small bony prominence felt at the base of the hypothenar eminence. Direct palpation over the FCU tendon and pisiform reproduces the pain specifically. This localization immediately distinguishes FCU tendinitis from ECU tendinitis, which is dorsal, and from carpal tunnel, which produces numbness rather than mechanical pain.
Pain With Wrist Flexion & Ulnar Deviation
Resisted wrist flexion — bending the wrist against resistance — and ulnar deviation are the primary provocative movements. Carrying objects with the wrist flexed, golf swings, baseball batting, and any gripping task that loads the FCU at its insertion provoke the pain. The FCU is the dominant wrist flexor on the ulnar side; when its insertion degenerates, any task demanding wrist flexion under load hurts.
Grip-Dependent Pain
The FCU contributes substantially to wrist stability during gripping. Many patients report that sustained gripping — carrying a grocery bag, holding a hammer or golf club, or gripping a steering wheel for extended periods — builds pain progressively during activity. The pain eases with rest and returns with repeated loading.
Activity-Related Pattern
Like all overuse tendinopathies, FCU tendinitis follows the classic activity-provoked pattern: pain builds with the offending activity and eases with rest. Patients often identify the specific task that causes flares — a golf round, a day of hammering, a weekend of yard work — and can trace the onset of symptoms to a period of increased loading.
Associated Ring or Small Finger Numbness
Numbness, tingling, or burning in the ring and small fingers alongside FCU pain indicates ulnar nerve involvement — either at the cubital tunnel (elbow) or Guyon's canal (wrist). This finding changes the management: nerve compression is evaluated with clinical examination and nerve conduction studies, and may need to be addressed alongside or instead of the FCU tendinitis.
Hand Weakness or Intrinsic Muscle Wasting
Weakness of grip or pinch, difficulty spreading the fingers, or visible wasting of the small muscles between the thumb and index finger (first dorsal interosseous) indicates significant ulnar nerve motor involvement — likely cubital tunnel syndrome rather than FCU tendinitis alone. This requires prompt nerve conduction study and surgical evaluation.
Dr. Graham's Treatment Protocol
The Same Stepped Approach as FCR Tendinitis
FCU tendinitis is the most straightforward of the wrist tendinopathies to treat — and the one where surgery is most rarely needed.
Wrist Brace Immobilization + Physical Therapy
A wrist brace holding the wrist in a neutral or slightly extended position reduces FCU loading at the pisiform insertion and gives the inflamed tendon sheath an opportunity to settle. Physical therapy addresses activity modification, loading technique, and strengthening of the wrist flexor-stabilizer complex. In Dr. Graham's experience, a meaningful proportion of FCU tendinitis patients improve on this step alone — often without needing the injection.
Corticosteroid Injection into the FCU Sheath
If immobilization and therapy are not sufficient, Dr. Graham places one corticosteroid injection into the FCU tendon sheath at the pisiform region. The injection target is the FCU sheath at the volar-ulnar wrist — accurately placed at the site of maximum tenderness. One injection only: the same rupture-risk rationale that applies to the FCR, ECU, distal biceps, and triceps. For patients who need further injection-based treatment, PRP is the next step.
MRI to Characterize the Tendon
If brace, PT, and one injection do not provide adequate lasting relief, MRI is ordered. This characterizes the degree of FCU tendon degeneration, confirms where along the tendon the pathology is located — at the pisiform insertion or more proximally — and guides surgical planning. MRI is not needed at the initial visit; it is reserved for the minority of patients who reach this step.
FCU Debridement
For the small number of patients who remain symptomatic despite the full conservative protocol, surgical debridement of the degenerated FCU tendon tissue — at the site identified on MRI, wherever degeneration is found along the tendon — resolves the problem effectively. The procedure is targeted: degenerated tissue is excised, healthy tendon is preserved, and the pisiform is inspected for any associated bone pathology. Recovery mirrors FCR: two weeks in a splint for comfort, then no restrictions.
Regenerative Treatment Option
Platelet-Rich Plasma
for FCU Tendinitis
FCU tendinopathy involves the same angiofibroblastic degeneration seen across the other overuse tendinopathies treated on this site — disorganized collagen that doesn't respond to rest or cortisone at the structural level. PRP delivers concentrated growth factors directly to the degenerative zone at the pisiform insertion, providing the biological stimulus for remodeling.
For FCU tendinitis specifically, PRP is most relevant in two situations. First, after one cortisone injection without lasting relief — the one-injection limit means PRP becomes the logical next injection-based option before surgery. Second, for patients who want to avoid any cortisone risk at this location and prefer a biologically targeted approach from the outset.
Given that FCU tendinitis already responds well to conservative management — and that surgery is rarely needed — PRP fits naturally into the pathway between one cortisone injection and any surgical conversation. It may be the step that allows patients to avoid surgery entirely. Dr. Graham is happy to discuss candidacy at your appointment. PRP is cash-pay and not covered by insurance.
Why PRP Fits Here
- ✓ Logical next step after the one permitted cortisone injection
- ✓ Targets FCU tendon degeneration — not just pain suppression
- ✓ No rupture risk — contrasts with repeated cortisone
- ✓ May avoid surgery in an already surgery-rare condition
- ✓ Accessible pisiform injection target — accurate delivery
- ✓ Cash-pay — candidacy discussed at consultation
Surgical Treatment — Rarely Needed
FCU Debridement
When conservative management truly doesn't hold, surgical debridement of the degenerated FCU tendon is effective and recovery is fast. The procedure is targeted to wherever MRI shows the pathology.
Anesthesia & Setting
Performed at Baptist Beaches Hospital or Horizon Surgery Center as a same-day outpatient procedure. Regional block (wrist or forearm) with or without sedation, or general anesthesia. Tourniquet on the upper arm. Operative time is typically 30 to 45 minutes. The ulnar nerve and ulnar artery are identified and protected throughout — both run in close proximity at the volar-ulnar wrist.
Volar-Ulnar Incision
A longitudinal incision is made over the volar-ulnar wrist, centered on the FCU tendon and pisiform region. The ulnar neurovascular bundle — the ulnar nerve and ulnar artery traveling through Guyon's canal — is identified and carefully protected. If cubital tunnel or Guyon's canal compression is being addressed at the same setting, the exposure is extended appropriately.
FCU Tendon Inspection
The FCU tendon sheath is opened and the tendon is inspected along its length — from the pisiform insertion proximally to wherever MRI indicated degeneration. The pisiform surface is also examined for any bony irregularity or degenerative change contributing to tendon irritation. The extent and location of tendon degeneration are confirmed under direct visualization.
Targeted Debridement
Degenerated angiofibroblastic tissue is excised at the site of pathology — wherever it is found on intraoperative assessment, consistent with the MRI findings. Healthy tendon tissue is preserved. If degeneration extends to the pisiform surface or pisohamate ligament origin, those structures are addressed at the same setting. The debridement is targeted: not a global procedure, but a precise excision of pathological tissue.
Closure & Splint
The wound is closed in layers and a volar wrist splint is applied for comfort. Sutures are removed at 10 to 14 days. The splint is worn for two weeks — for comfort only, not to protect a repair. After two weeks: no restrictions on wrist use or activity.
Recovery
What to Expect After FCU Debridement
Recovery from FCU debridement is straightforward — two weeks of splinting for comfort, then no restrictions.
Splint for Comfort
Volar wrist splint for wound comfort and swelling control. Gentle finger motion encouraged from day one. Sutures removed at 10–14 days. Ice and elevation for swelling. Oral pain medication as needed.
No Restrictions
After the two-week splint period: no activity restrictions. Return to work, sport, and daily activities as comfort allows. No formal physical therapy routinely required. Residual swelling continues to subside over 4 to 6 weeks.
Full Return
In Dr. Graham's experience, most patients return to full activity — including manual labor, golf, and gripping sports — within 4 to 6 weeks of surgery. Recovery is paced by comfort, not a fixed timeline.
“Dr. Graham was awesome. He explained everything about my surgery in a way I could understand. He is very personable with an excellent bedside manner.”
Common Questions