Tendon transfers for rheumatoid tendon attrition rupture

Indications

• In rheumatoid arthritis patients, tendon rupture is a result of synovitis or attrition over a deformed bone. Common bony pathologies include caput ulnae syndrome (dorsal prominence of the ulna head leading to extensor tendon rupture; Fig. 37.1 ) and Mannerfelt syndrome (flexor pollicis longus [FPL] rupture caused by a volar scaphoid osteophyte.

  

• The most ruptured tendon in rheumatoid patients is the extensor digiti minimi (EDM), followed by the extensor digitorum communis (EDC) tendons to the small finger (SF), ring finger (RF), middle finger (MF), and index finger (IF; in that order) and the extensor pollicis longus (EPL). On the flexor side, FPL rupture is most common; the flexor digitorum profundus (FDP) and superficialis (FDS) tendons are rarely involved.

• Direct repair of ruptured tendons is not possible because the tissue quality is poor, and tendon grafting is not reliable because of proximal myostatic contracture from months of delayed repair. Tendon transfers are indicated to restore motor function in rheumatoid patients with attritional tendon rupture. The specific procedure depends on the number and function of ruptured tendons. Options include end-to-side repair to an intact adjacent tendon or transfer of an injured tendon to the distal stump of a ruptured tendon ( Table 37.1 ; Fig. 37.2A–D ).

  TABLE 37.1

  Number of Ruptured Tendons and Treatment Considerations

  No.	Impairment	Diagnosis	Preferred Option	Alternative Option
  1.	Inability to extend small finger	Rupture of EDM at ulnar head	End-to-side repair of EDM to EDC to ring finger
  2.	Inability to extend small and ring fingers	Rupture of EDC to ring and small under extensor retinaculum and EDM at ulnar head	EIP transfer to EDC to ring and EDM
  3.	Inability to extend small, ring, and long fingers	Rupture of EDC to long, ring, and small under extensor retinaculum and EDM at ulnar head	EIP transfer to EDC to ring and EDM End-to-side repair of EDC to index and long
  4.	Inability to extend small, ring, long, and index fingers	Rupture of EIP, EDC to index, long, ring, and small under extensor retinaculum, and EDM at ulnar head	FDS long to EDC to index and long FDS ring to EDC to ring, small and EDM	ECRL or ECRB can be considered
  5.	Inability to extend thumb	Rupture of EPL at Lister tubercle	EIP to EPL	ECRL to EPL EDM to EPL
  6.	Inability to extend thumb and small, ring, long, and index fingers	Rupture of EPL at Lister tubercle, EIP, EDC to index, long, ring, and small under extensor retinaculum, and EDM at ulnar head	FDS long to EPL and EDC to index FDS ring to EDC long, ring, small, and EDM
  7.	Inability to flex thumb	Rupture of FPL in carpal tunnel	BR to FPL	ECRL to FPL FDS long to FPL Thumb IP joint fusion
  8.	Inability to achieve independent flexion of PIP joint	Rupture of FDS	PIP joint synovectomy to prevent rupture of FDP
  9.	Inability to flex DIP joint	Rupture of FDP	DIP joint arthrodesis	Tenodesis of DIP joint
  10.	Inability to flex IP joints	Rupture of FDS and FDP	Staged flexor tendon reconstruction

  BR , Brachioradialis; DIP , distal interphalangeal; ECRB , extensor carpi radialis brevis; ECRL , extensor carpi radialis longus; EDC , extensor digitorum communis; EDM , extensor digiti minimi; EIP , extensor indicis proprius; EPL , extensor pollicis longus; FDP , flexor digitorum profundus; FDS , flexor digitorum superficialis; FPL , flexor pollicis longus; IP , interphalangeal; PIP , proximal interphalangeal.

  

• Bony pathology must be addressed at the time of tendon transfer to prevent progressive deformity and rerupture of the reconstructed tendons. Distal ulna excision (see Chapter 49 : Distal Ulna Resection [Darrach Procedure]) or osteophyte excision can be performed as part of the procedure.

Clinical examination

• The patient is examined for areas of swelling, tenderness, previous scars, and deformity.

• Examine the wrist and distal radioulnar joint for pain and instability (See Chapter 49 : Distal Ulna Resection [Darrach Procedure]).

• Active and passive range of motion (ROM) of all joints is assessed. Inability to actively flex or extend a joint raises suspicion for tendon rupture.

• Patients with isolated EDM rupture may be able to extend the SF through the EDC; however, they will not be able to independently extend the SF with the other fingers flexed.

• Patients with rupture of the EDC to one finger may be able to extend the finger through juncturae to adjacent fingers. When more than one EDC is ruptured, the deformity is more obvious ( Fig. 37.3 ).

  

• EPL function is tested by placing the patient’s hand flat on a table (palm down) and asking them to lift the thumb off the table. Intact retropulsion signifies intact EPL function ( Fig. 37.4 ).

  

• Lack of finger extension in RA is also sometimes caused by ulnar subluxation of the tendons over the head of the metacarpal ( Fig. 37.5 ) or, rarely, from posterior interosseous nerve palsy caused by elbow synovitis. To differentiate between these causes, passively extend the finger and ask the patient to hold it in place. Patients with tendon rupture or nerve palsy will be unable to maintain extension; however, patients with extensor tendon subluxation will maintain extension because the extensor tendon is centrally relocated over the metacarpophalangeal (MCP) joint. Patients with tendon rupture will lose the tenodesis effect of finger extension with wrist flexion. Tenodesis is preserved in nerve palsy.

  

• The EIP and FDS to the RF and MF are often used as donor tendons in patients with multiple extensor tendon ruptures, and their function must be checked and documented preoperatively. EIP is intact when independent extension of the IF is possible with the other fingers flexed ( Fig. 37.6 ). To assess FDS function, all other digits are blocked, and the patient is asked to flex the finger in question at the proximal interphalangeal (PIP) joint. FDP share a common muscle belly and therefore, independent flexion of any finger with the others restrained requires an intact FDS tendon. Similarly, the FDP is assessed by blocking PIP flexion of the possible donor digit in question and asking the patient to flex the DIP joint ( Fig. 37.7A-B ).

  
  

Imaging

Standard three-view wrist radiographs are required to evaluate the distal radioulnar (DRU), midcarpal, and radiocarpal joints.

Surgical anatomy

• A detailed understanding of the flexor ( Fig. 37.8 ) and extensor ( Fig. 37.9 ) tendon anatomy is required.

  
  

• Tendons in RA can be directly invaded by synovial pannus within tenosynovial sheaths (extensor retinaculum, carpal tunnel, and digital flexor sheath), or may rupture as a result of ischemia caused by pressure from a proliferative synovitis; this results in regions where the tendon is in close relation to joints (DRU, radiocarpal, PIP joints).

• Attritional rupture frequently affects the EDM at the ulna head, EPL at the Lister tubercle, and FPL in the carpal tunnel caused by a flexed scaphoid.

• Dorsal ulnar subluxation is commonly described in RA, but this is a misnomer; the ulna is the fixed axis of the forearm. The radius subluxates volarly, which gives the impression of dorsal ulna prominence ( Fig. 37.10 ).

  

• It is important to identify the cause of the tendon rupture at the time of tendon reconstruction. This may require synovectomy or procedures to address joint instability and osteophytes. For example, if the patient has SF extensor tendon rupture, it is highly likely that other extensors will rupture subsequently (Vaughan-Jackson syndrome). Tenosynovectomy, distal ulna excision, and tendon reconstruction are the preferred treatments to prevent progressive disease.

Positioning and equipment

• The patient is positioned supine with the arm extended and hand pronated on a hand table. An upper arm tourniquet is placed.

• A tendon passer and tendon weaver should be available for tendon transfers. Intraoperative fluoroscopy, an oscillating saw, and a bur are required if bony resection (Darrach) is planned.

Exposures

• A 6-cm longitudinal incision is made over the dorsum of the wrist in line with the MF metacarpal to expose the EDC tendons within the fourth compartment. When present, previous incisions are used ( Fig. 37.11 ).

  

• Skin flaps are elevated at the level of the extensor retinaculum ( Fig. 37.12 ).

  

• The extensor retinaculum is incised using a stair-step design to facilitate closure at the end of the case ( Fig. 37.13 ).

  

• The intercompartmental septae are divided between the extensor compartments; this converts the extensors into a single compartment and exposes the total extent of synovitis.