Jersey finger (rugby finger) is an avulsion of the flexor digitorum profundus tendon (FDP) from its distal insertion on the distal phalanx (zone I). The ring finger is most commonly affected. Since the ring finger protrudes the farthest in the grasping position, it is more susceptible to FDP avulsion causing an inability to flex at the DIPJ.
Clinically Relevant Anatomy
FDP is one of the deep muscles of the anterior compartment of the forearm. It is the hybrid muscle supplied by two different nerves: medial half is supplied by ulnar nerve and lateral half is supplied by anterior interosseous nerve. It is the chief gripping muscle when the wrist is extended. It is the sole flexors of Distal Interphalangeal (DIP) Joint of digit 2nd to 5th.
Mechanism of Injury
Majority of injuries occur in the ring finger at the point of insertion which is the weakest point in the tendon. An injury occurs to the finger if it is caught in the jersey of a player while the little finger continues to flex and extension of FDP occurs as the tackled player runs away. A forceful extension while contraction of FDP leads to avulsion of the tendon.
- Inability to flex DIP joint actively
- Pain, ecchymosis, and edema may be present
The classification system of a jersey finger injury is based on the level of tendon retraction and the presence or absence of a fracture. Types I-III was first described by Leddy and Packer in 1977, and two additional types, IV and V, have since been added.
- Type I: FDP tendon retracts to the palm at the lumbrical origin.
- Type II: FDP tendon retracts to the A3 pulley at the proximal interphalangeal (PIP) joint.
- Type III: Avulsion of a large bony fragment. Both FDP tendon and fracture fragment retract to the A4 pulley, as the bone fragment limits further retraction.
- Type IV: Avulsion of a large bony fragment with an accompanying rupture of the FDP tendon off the bony fragment. Since the avulsed FDP is not attached to the bony fragment, the FDP retracts into the palm.
- Type V: Avulsion of a large bony fragment, accompanied by another significant fracture of the distal phalanx.
Physical examination along with X-rays and Ultrasound to rule out fractures is important. MRI can help in a detailed evaluation of the injury and may help in identifying the extent of tendon retraction however it is rarely used. The following test is used to check FDP avulsion :-
- Phalanx fracture
The treatment of Jersey finger is primarily surgical and conservative management is only considered when surgery cannot be performed due to complications. Surgical management is definitive management and should be performed as early as possible, usually within 3 weeks of injury. Surgical salvage procedures for late presentation include DIP joint arthrodesis, tenodesis, and staged tendon reconstructions. A number of surgical techniques are used to treat avulsion injuries of the FDP, including the following:
- the Bunnell pull-out suture technique
- suture anchor repair
- repair of the tendon with incorporation of the volar plate.
The latter is the most recent of the described techniques, and clinical outcome studies are still in development. The pull-out suture procedure has traditionally been the most commonly used technique.
Athletes can expect 8–12 weeks of loss of play following surgical treatment. A sport specific hand rehabilitation protocol is considered for athletes following surgery with respect to their position during play and level of competition which consists of -
- Dorsal Blocking Splint (DBS)
- Passive Range of motion (ROM) exercises in early post-operative phase
- Active or assisted ROM exercises
- Place and hold exercises
- Strengthening/power grasping exercises
- Scar massage
- Tendon gliding exercises
Clinical Orthopedic Rehabilitation (second edition) - S. Brent Brotzman, Kevin E. Wilk
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