Forearm, Wrist and Hand, Lecture notes of Orthopedics

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Forearm, Wrist and Hand Median Nerve  Roots: C5/C6-T1  Motor Function o Innervated the flexor and pronator muscles in the anterior compartment of the forearm (Except the flexor carpi ulnaris and half of flexor digitorum profundus) o Supplies innervation to the thenar muscles (Except adductor pollicis) and the lateral 2 lumbricals in the hand  Sensory Function o Palmar cutaneous branch: Lateral aspect of the palm o Digital cutaneous branch: Later 3.5 fingers on the palmar surface (including nailbeds) Ulnar Nerve  Roots: C8-T1  Motor Function o Flexor carpi ulnaris and medial half of flexor digitorum profundus o Hand: hypothenar muscles, medial 2 lumbricals, adductor pollicis, palmar and dorsal interossei (for abduction and adduction), palmaris brevis  Sensory Function o Innervates anterior and posterior surfaces of medial 1.5 fingers and the associated palm area Radial Nerve  Roots: C5-T1  Motor Function o Innervates the triceps brachii and extensor muscles of the forearm  Sensory o Innervates most of the skin on posterior side of forearm o Dorsal surface of lateral 3.5 fingers (excluding nail beds) and dorsal surface of lateral side of the palm Fracture of the Shafts of the Radius and Ulna Since both bones are joint together, it is unlikely that there is injury to only one bone at the shaft level.  Monteggia Fracture: Fracture of proximal 1/3 ulna with dislocation of radial head  Galeazzi Fracture: Fracture of distal 1/3 radial shaft with dislocation of DRUJ Shaft fractures are usually treated surgically as they act as a joint allowing for pronation and supination. Reduction of the radial head or ulna is also essential Fracture of the Distal end of the Radius This is the most common fracture in orthopedics. May be intra or extra articular. a) Colles’ Fracture Distal radial fracture within 2.5cm (1 inch) of the wrist There is a dorsally displaced fragment There may be impaction of the distal fragment The styloid process of the ulna is often avulsed Dinner fork deformity May predispose to carpal tunnel Look out for associated scaphoid fracture A Colles’ fracture is almost always produced by a fall on the outstretched hand. Some complications of this fracture may include: o Median nerve symptoms o Rupture of a tendon crossing the fracture line ex: extensor pollicis longus Treatment: Back (Dorsal) plaster slab or volar slab (as a full cast can interrupt circulation). The fracture is usually reduced by manipulation under anesthesia. In the child, this fracture is usually of greenstick type and reduction is rarely necessary. 2-3 weeks in a plaster slab is sufficient to allow healing to occur. b) Smith’s Fracture AKA reverse Colles’ fracture The fracture piece of bone is displaced anteriorly (towards the palm) Fall on the back of the hand Rupture of the Ulnar Collateral Ligament of the Thumb AKA Skier’s Thumb This is a partial or complete rupture of the ulnar collateral ligament of the MCPJ of the thumb and is caused by over-abduction. Treatment: Minor instability can be treated with a scaphoid-type plaster-cast. If it instability is obvious, surgical repair followed by plaster immobilization is advisable. Key points in the management of hand injuries:  Amputation in severe injuries may be the best option  Preserve as much thumb as possible  An insensate digit is almost useless  Complex crush injuries are best managed in specials centres with a hand service Acute Infections  Acute Paronychia – Infection under the nail-fold (normally bacterial)  Apical Abscess – A small collection of pus under the end of the nail  Intradermal Abscess – A collection of pus on the palmar surface of the finger or hand  Pulp Space Infection  Web Space Infection – Infection between fingers  Deep Palmar Space Infection If osteomyelitis occurs, the infected bone may need to be excised. Suppurative Tenosynovitis This is a serious condition usually originating from a penetrating injury, which may be minor. There is bacterial invasion of the flexor tendon sheath. The tendon sheath fills with fluid and later, pus. The infection may extend to the deep palm. The digit is swollen, very painful and tender along the whole length of the sheath. All movements are painful. The most common cause is penetrating trauma. Neoplastic Conditions Metastatic tumours are relatively uncommon in the forearm and hand. Pain in this area may be referred from a bronchial neoplasm affecting the apex of the lung and invading the brachial plexus (Pancoast tumour) Primary Tumours: Enchondromata (benign tumour originating in cartilage) arising in the finger are relatively common De Quervain’s Tenosynovitis This condition is due to thickening of the tendon sheaths of the abductor pollicis longus and extensor pollicis brevis where they cross the radial styloid. Repeated movements may be responsible for some cases, however the cause is not fully established. It is a tenosynovitis of the first dorsal extensor compartment (There are 6 extensor compartments) – The 1st compartment is the APL and EPB Tenosynovitis = Inflammation of the fluid filled sheath It is very typical in lactating mothers and hence it is sometimes referred to as Mummy’s Thumb. The patient complains of pain at the site (distal radius), made worse by gripping and by extending the thumb. Forced flexion of the thumb whilst the wrist is deviated to the ulnar side also causes pain. There is localized tenderness and often a swelling over the radial styloid. Treatment: A hydrocortisone injection may give rapid relied. Resistant cases can be treated by opening the sheath surgically, making sure that all the tendinous strips are completely freed (We have to make sure that we release both tendons APL and EPB as sometimes they may have a separate sheath). Trigger Finger This is a similar condition affecting the sheath of the flexor tendon and causing the tendon to stick as it passes under a tendon A1 pulley. The patient may be unable to extend the finger actively from the fully flexed position. A nodule is usually palpable at the site of thickening, opposite the head of the metacarpal. This condition occurs occasionally in young babies, almost always affecting the thumb (clasped thumb) Treatment: It may resolve spontaneously. Steroid injections into the sheath may be effective, but if it fails, it can be cured by longitudinal division of the tendon pulley. Both trigger finger and De Quervain’s can be early manifestations of RA. Dupuytren’s Contracture The palmar fascia thickens and pulls mainly the 4th and 5th finger into fixed flexion. This is a condition affecting the collagenous tissue of the palmar fascia. There is frequently a family history. It is occasionally related to cirrhosis of the liver, diabetes and rarely to drugs used to treat epilepsy. It affects middle aged men much more commonly than women. Clinical Features  The characteristic feature is a very slowly progressing flexion contracture of the fingers and thumb. It is usually bilateral but may be more severe on one side  The palmar fascia feels thickened and nodular and tends to pucker the overlying skin. Definite bands can be felt running along the sides of the fingers due to thickening of the lateral extensions of the fascia  The PIPJ and MCPJ are usually the most affected Normally, the palmar fascia consists of collagen type I, but in Dupuytrens, it is changed to type III which is significantly thicker. Treatment: Usually surgery is necessary for the established contracture with symptoms. Occasionally, a finger may be better amputated if deformity is very. Severe Osteoarthritis OA may affect joints damaged by disease or injury. For ex: OA of the wrist following a non- united scaphoid fracture. In OA, breakdown of joint cartilage and bone occurs, causing joint pain and stiffness. One of the main causes is age (Wear and tear), other causes include torn cartilage, dislocated joints, ligament injuries and obesity. OA of the joint between the trapezium and base of the first metacarpal is common (1 st CMCJ OA) – patient comes complaining with pain at the base of the thumb which may radiate upwards. First line treatment would be anti-inflammatories, 2nd option is hydrocortisone injections and last resort is removal of the trapezium (Trapeziectomy) There could also be arthritis between the scaphoid and the trapezium and the treatment for this would be to fuse them together. Nodal OA: Heberden’s Nodes at the DIPJ and Bouchard’s nodes at the PIPJ Squaring of the CMC joint of the thumb is also a feature of hand OA Rheumatoid Arthritis