Tendon Injury Repair
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Direct answer
"No man's land" — Bunnell's name for flexor zone II, from the A1 pulley to the superficialis insertion — described an era when sheath repair was avoided; the modern standard repairs both tendons primarily with a multi-strand core suture plus a circumferential epitendinous stitch and begins controlled motion within days, because tendons heal best under early controlled stress. Verdan's flexor zones I to V dictate prognosis and approach, the A2 and A4 pulleys must be preserved or reconstructed to prevent bowstringing, and rehabilitation programmes (Duran, Kleinert, Belfast) exist to balance these forces; the repair is weakest in the first fortnight and protected for six weeks.
What you must remember
- Flexor zones: I distal to superficialis insertion; II from A1 to that insertion; III palm; IV carpal tunnel; V forearm.
- Zone II injuries today get primary repair of both superficialis and profundus under magnification and tourniquet; the old grafting doctrine has retired.
- Suture architecture: a modified Kessler or Tajima core of 3-0 or 4-0 plus a running 6-0 epitendinous stitch; four or six strands buy strength for earlier active motion; partial clean lacerations over about half the width are trimmed or repaired.
- The A2 and A4 pulleys are structural: sacrificing either invites bowstringing and lost excursion.
- Jersey finger (Leddy): type I retracts into the palm, both vincula torn — repair within about a week; type II stalls at the proximal joint, long vinculum intact; type III carries a bony avulsion caught at A4.
- Rehabilitation: controlled passive motion (Duran) or rubber-band-assisted extension (Kleinert) in a dorsal blocking splint; early active protocols begin within days in compliant adults; strength is reasonable by twelve weeks.
- Mallet finger (extensor zone 1) is treated by continuous extension splinting for six to eight weeks, including a bony avulsion fragment.
- Central slip injury at extensor zone 3: positive Elson's test; untreated it becomes a boutonnière deformity.
- Complications: rupture in around five per cent, and adhesions treated by tenolysis at three to six months once healed and cooperative with therapy.
A zone II repair from knife to keyboard
A 24-year-old chef slices the middle finger at the base of its digit; the wound sits in zone II. In theatre, under tourniquet and loupes, the wound is extended with Bruner's zigzag incisions avoiding right angles across flexion creases. Both tendons are found — the profundus having slid distally, the superficialis caught at the chiasma — and retrieved with a catheter, respecting the sheath and the A2 and A4 pulleys. The repair is a four-strand core with a running epitendinous suture, tested through a full passive range for gapping and catching; the sheath is loosely closed over it. A dorsal blocking splint holds the wrist flexed about thirty degrees, the metacarpophalangeal joints at seventy and the interphalangeal joints nearly straight. From day three to five the Belfast programme begins — short-arc active flexion within the splint — because motion glides the tendon and limits adhesion while the core carries the load. Weeks two to six are protected active use, then strengthening; at four months an intact but poorly gliding tendon earns a tenolysis, provided the patient will work afterwards.
Where candidates lose marks
The commonest loss is quoting "no man's land" as a reason not to repair — examiners mark it outdated; the correct line is that zone II repair is demanding, needs both tendons and does well in trained hands. The second is confusing the Leddy types, particularly type I (palm-level retraction, urgent) with type II (proximal joint-level, semielective) — the urgency hangs on the vincula. The third is splint architecture: wrist extended or metacarpophalangeal joints straight unloads the repair wrongly and invites rupture. And tenolysis offered at six weeks forgets that the tendon must be healed and the joints supple — three to six months is the window.
Frequently asked questions
Which structures define the boundaries of flexor zone II?
Distally, the insertion of superficialis; proximally, the A1 pulley. Between them lie the tight sheath, the chiasma and both tendons — Bunnell's "no man's land".
Why must the A2 and A4 pulleys be preserved?
They tether the tendons against the phalanges; without them the tendon bowstrings, wasting excursion and producing extension lag. A destroyed pulley needs reconstruction.
What distinguishes a Leddy type I jersey finger?
Avulsion of the profundus with rupture of both vincula, allowing retraction into the palm; the tendon loses its blood supply, so repair must occur within about a week. Type II retains the long vinculum and tolerates later repair.
When can active finger flexion begin after repair?
In compliant adults on early-active protocols such as Belfast, short-arc active flexion starts between the third and fifth day in a dorsal blocking splint for six weeks.
What is Elson's test and what does a positive result show?
With the proximal interphalangeal joint held flexed to ninety degrees, the patient tries to extend the middle phalanx; a firm extension force at the distal joint instead of the middle indicates central slip rupture, before a boutonnière develops.