My Hand Hurts
Dawn M. LaPorte, MD, FAAOS
Seth D. Dodds, MD, FAAOS
Dr. LaPorte or an immediate family member serves as a board member, owner, officer, or committee member of ACGME – Orthopaedic RRC, American Orthopaedic Association, American Society for Surgery of the Hand, and Ruth Jackson Orthopaedic Society. Neither Dr. Dodds nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter.
Four classic hand surgery pathologies are described, answering the question, Why does my hand hurt? These four problems range in their anatomic focus and etiology. One of the most fulfilling aspects of hand surgery is the ability to treat conditions related to the entire musculoskeletal system. In general, orthopaedics tends to focus on bones and joints. However, in the adventurous realm of hand surgery, the conditions to be treated range from the foundation of the bone, to the moving articulation, to the ligaments that maintain stability, to the muscles and tendons that power the joints, to the blood vessels that provide hand vascularity, to the nerves that supply motor and sensory function, and finally to the skin that envelops the hand in its composite.
CARPAL TUNNEL SYNDROME
Most common compression neuropathy; affects 3% to 8% of adults in the general population
Caused by increased pressure within the carpal tunnel, resulting in compression of the median nerve and characterized by pain
and paresthesias on the palmar-radial aspect of the hand, often worse at night
The cause is not typically identified; however, carpal tunnel syndrome (CTS) has been associated with trauma, repetitive motion, and different medical conditions.
Risk factors for CTS:1
Seen more in females than males (3:1 ratio)
Diabetes (odds ratio, 1.9)
CTS is frequently bilateral (16% to 87%).
Nerve roots C5 to T1 contribute to the median nerve, but C5 input is not consistent.
The median nerve arises from the medial and lateral cords of the brachial plexus. It runs lateral to the brachial artery and superficial to the brachialis and deep to the biceps in the arm and crosses anterior to the brachial artery and then progresses into the forearm medial to the artery. It lies medial to the brachial artery at the antecubital fossa and both lie medial to the biceps tendon. It then enters the forearm between the ulnar and the humeral head of the pronator teres and, distally, passes deep to the flexor digitorum superficialis (FDS) at its proximal arch and travels between the FDS and the flexor digitorum profundus (FDP).
The anterior interosseous nerve arises from the median nerve just distal to the arch of the FDS and the palmar cutaneous branch of the median nerve branches from the main nerve 5 to 7 cm proximal to the volar wrist crease. The median nerve passes between the flexor carpi radialis and the FDS at the distal forearm before entering the carpal tunnel. The recurrent motor branch typically branches radial to the median nerve through the carpal tunnel to supply the thenar muscles. Distal
to the carpal tunnel, the median nerve branches into digital nerves to supply sensation to the thumb, index, long, and the radial ring finger.
The borders of the carpal tunnel include the transverse carpal ligament volarly, the carpal bones dorsally, the hook of the hamate and triquetrum ulnarly, and the scaphoid tubercle and trapezium radially.
Ten structures pass through the carpal canal—nine flexor tendons and the median nerve (Figure 1). The tendons are the FDS to the index through the little finger, the FDP to the index through the little finger, and the flexor pollicis longus.
Increased pressure on the median nerve is caused by decreased space in the carpal canal, which can be secondary to bony anatomy, for example, a fracture, flexor tenosynovitis. Increased pressure on the nerve results in decreased perfusion and in turn compromised function of the nerve.
The recurrent motor branch is the only motor branch to arise from the median nerve at the level of the carpal canal. It innervates the thenar muscles, including the abductor pollicis brevis (APB), which provides thumb opposition.
Pertinent History/Physical Examination Findings
Typical complaints: numbness and/or tingling in a median nerve distribution, frequently worse at night.
Patients may awaken at night with pain and/or numbness and feel as if they have to shake out their hand(s) (flick sign has 90% sensitivity/specificity).
Patients may complain of weakness or dropping objects or difficulty with fine motor tasks.
Diagnosis is frequently made through a comprehensive history and examination and may be confirmed with electrodiagnostic testing.
Typical examination findings
Subjective diminished light touch sensation in the thumb, index, and long, and radial half of the ring finger
Diminished two-point discrimination
Positive Tinel test (Figure 2)—paresthesias in a median nerve distribution after tapping over the median nerve at the wrist (sensitivity 38% to 100%, specificity 55% to 100%)
Positive Phalen test—paresthesias in a median nerve distribution after holding the wrist hyperflexed for 30 seconds (note: maintain the elbow in full extension so as not to confound with compression of the ulnar nerve) (sensitivity 42% to 85%, specificity 54% to 98%)2
Positive Durkan test—paresthesias in a median nerve distribution after holding pressure for 30 seconds over the carpal tunnel
Durkan compression test has been shown to have the highest sensitivity for CTS (83% to 89%).3
More advanced cases: atrophy of the thenar muscles and weakness in opposition of the thumb, tested by assessing strength against resisted opposition (Figure 3)
Figure 3 A, Clinical photograph from a 72-year-old woman with thenar atrophy associated with advanced carpal tunnel syndrome. B, Clinical photograph shows testing thumb opposition (abductor pollicis brevis) strength against resistance.
The CTS-6 is a validated scale to support a high likelihood of CTS and can also measure responsiveness to release; it is based on symptoms in the median nerve distribution, nocturnal numbness, thenar atrophy or weakness, positive Phalen test, positive Tinel sign, and loss of two-point discrimination.4
Patients may have a double crush syndrome or compression at multiple levels, and examination of a patient with numbness and tingling in the hand should always include examination of the cervical spine.
Differential diagnosis includes cervical radiculopathy, thoracic outlet syndrome, pronator syndrome, and polyneuropathy.
Ultrasonography can be used for diagnosis of CTS.
Typically the cross-sectional area of the median nerve is measured at the proximal carpal tunnel.
Gold standard for diagnosis: nerve conduction study and electromyogram (EMG)
Electrodiagnostic studies are typically performed by a neurologist or physiatrist and measure sensory and motor conduction in addition to the EMG.
Prolonged sensory and or motor latency indicates a loss of myelin, and EMG changes (in the APB for CTS) indicate axonal loss.
Electrodiagnostic studies can confirm the presence and severity of compression as well as the level or levels of compression and which nerve or nerves are affected.
The first line of treatment for CTS is a cock-up wrist splint to be worn while sleeping.
The goal is to prevent flexion of the wrist at night and therefore decrease pressure on the median nerve.
If a patient has persistent symptoms despite nighttime splinting for at least 1 month, a trial of corticosteroid injection at the carpal canal may be considered. The injection can be both diagnostic and therapeutic.
Up to 80% of patients have improvement initially with corticosteroid injection; however, only 20% to 31% have persistent relief at 1 year.
If a patient has relief with corticosteroid injection but then symptoms recur, they should have an excellent prognosis with surgical carpal tunnel release (CTR).
CTS in pregnancy will usually resolve after delivery.
Initial treatment is with nighttime splinting. Corticosteroid injection is considered safe during pregnancy and is recommended if splinting does not resolve symptoms.
CTR is not frequently necessary in pregnancy but can be considered (with local anesthesia) if symptoms persist despite nonsurgical measures.
Patients who have persistent symptoms despite nonsurgical measures—nighttime splinting plus or minus corticosteroid injection—are candidates for CTR.
Patients who present initially with weakness or thenar atrophy or who have EMG changes should be encouraged to pursue CTR directly to prevent progression of motor loss.
CTR surgery can be performed as an open or endoscopic procedure.
The literature shows that long-term results are comparable between open and endoscopic procedures. There is a slightly increased risk of nerve injury with endoscopic CTR and an earlier return to work with the endoscopic release. The decision between open or endoscopic surgery is frequently based on surgeon preference or experience.
The surgery is performed under tourniquet, typically with local anesthesia plus or minus sedation, but can be performed wide awake with local anesthesia and no tourniquet.
A longitudinal incision is marked in the palm in line with the ring digit extending distally from the Kaplan cardinal line to proximally 5 mm distal to the distal wrist crease (Figure 4).
Make an incision through the skin and carry it through the palmar fascia (longitudinal running fibers), exposing the transverse carpal ligament (transverse running fibers).
Palpate the hook of the hamate, which is the ulnar border of the transverse carpal ligament.
The transverse carpal ligament is split in a longitudinal fashion just radial to the hook of the hamate, taking care to prevent injury to the underlying median nerve.
Releasing the transverse carpal ligament at its more ulnar aspect decreases the risk of injury to the recurrent motor branch in the rare incidence of a transligamentous branch.
The ligament should be split distally to the level of the sentinel fat (indicating the vascular arch) and proximally under direct visualization.
The patient does not bear weight on their hand and ideally does no lifting beyond a cup of coffee for 2 weeks.
The patient returns at 2 weeks for a wound check, sutures are removed, and the patient can gradually resume activity.
A small number of pills (approximately 5) of tramadol or Tylenol #3 may be given, though most patients will do well solely with over-the-counter medication, acetaminophen or ibuprofen.
Anatomic variants such as a transligamentous recurrent motor branch may put the nerve at risk during surgical release. In the initial postoperative period, watch for signs of infection.
Patients who have pain or nighttime waking preoperatively will often have relief of those symptoms shortly after surgery.
The numbness and paresthesias can gradually improve over the course of 1 year.
The most common reason for persistent symptoms after CTR is an incomplete release. Other possible causes for persistent symptoms include double crush and incorrect diagnosis.
Endoscopic CTR (Figure 5)
Endoscopic CTR uses a thin tube device with a camera attached (endoscope) guided through a small transverse incision in the wrist.
The endoscope allows the surgeon to directly see the internal structures of the wrist, including the transverse carpal ligament, without opening the area with a standard longer incision.
The device contains both the camera and the cutting tool and, during endoscopic CTR, the transverse carpal ligament is cut, releasing pressure on the median nerve.
The blade is elevated just proximal to the sentinel fat and then withdrawn slowly, cutting the ligament from distally to proximally, completely releasing the transverse carpal ligament.
Nighttime splinting has been reported to result in 75% relief at 18 months.
53% to 80% of patients have initial symptom relief after corticosteroid injection; however, only 20% to 31% remained symptom free at 12 months.5,6
Long-term outcomes after open and endoscopic CTR are reported to be good or excellent in 75% to 90% of patients, with recurrence reported in 4% to 57% of cases.
Endoscopic CTR is associated with earlier return to work and earlier recovery of grip and pinch strength compared with open CTR but no difference at 6 months.
Endoscopic CTR has also been reported to have a higher risk nerve injury (usually transient) and lower risk of scar tenderness.
Some studies suggest a higher incidence of recurrence with techniques other than open CTR (but the numbers to support this are small).
The most common cause of persistent symptoms after CTR is incomplete release.
Top 10 Knowledge Drops for Your Rotation
CTS is the most common compression neuropathy.
CTS is characterized by numbness and tingling in the thumb, index and long fingers, and radial aspect of the ring finger.
Symptoms are often worse at night.
Patients may also have weakness in the hand, especially with thumb abduction and opposition.
The only motor branch affected in CTS is the recurrent motor branch that innervates thenar muscles, including the APB.
The contents of the carpal canal include the median nerve and nine tendons—FDS to the index finger through little finger, FDP to the index finger through little finger, and flexor pollicis longus.
If the patient has significant weakness/atrophy of the APB or EMG changes consistent with denervation, most surgeons recommend CTR rather than pursuing continued nonsurgical treatment.
The most significant risk of surgical release of the carpal tunnel is median nerve injury.
The primary advantage of endoscopic CTR is a slightly sooner return to work (approximately 2 weeks) compared with open release. At 1 year, both groups are similar.
The disadvantage of endoscopic CTR is a very small increase in the incidence of median nerve injury compared with open release.