gms | German Medical Science

Objectives/Interrogation: The lumbrical plus disease is also described as Park's Syndrome or Paradoxical extension.

The lumbrical muscle's proximal origin is from the tendon of flexor digitorum profundus in the palm, while the distal insertion is dorsal on the radial bundle of extensor tendon on the back of proximal phalanx.

If for several reasons the proximal origin of lumbrical muscle shifts proximally or becomes contracted, the increased tension will be applied trough the radial bundle on the dorsum of the finger causing paradoxical extension of the PIP joint while attempting to flex the fingers.

Possible causes of this mechanism may be: avulsion of FDP, partial severance of FDP, amputation through the middle phalanx, over long flexor tendon graft, adhesions between muscle and tendon sheath.

The paucity of published material on this condition testifies to its rarity or the condition still going un-recognised after many years since its initial description

Methods: We reviewed the cases of lumbrical plus observed in our experience, following tendon graft, tendon transfers, amputation and other cases of adhesion between lumbrical muscle and tendon sheath.

On 22 tendon graft who underwent to complete follow up, we found 2 cases of paradoxical extension; only one of 16 Paneva-Holevich procedures; one case after amputation of middle finger at distal inter-phalangeal joint;2 cases following tendon transfer of FS of ring finger pro FP; 4 cases following hand's fractures and 2 cases after tendon suture;

All lumbrical plus diseases were treated with lumbrical release at the proximal origin on the tendon of Flexor digitorum profundus, with successful results.

We had only one case of recurrence.

Results and Conclusions: From 1973 to 2016 we observed a total of 12 cases of lumbrical plus.

The digits more frequently involved were middle finger(5 patients), ring finger (2 patients), little finger(5 patients), little finger was also the finger more frequently injured. Middle finger is the most commonly involved as Park described. We found a relationship with surgeon experience in tendons reconstructive surgery (more frequent in older graft performed).

Our experience confirms that is an un-frequent disease and often diagnosis is missed or delayed.

We recommend Importance of clinical tests and to consider the diagnosis when we have a patient who seems un-cooperative during rehabilitation.