MOJ Orthopedics & Rheumatology Physical Examination: Extended OK Sign Abstract Research Article This article presents an elaboration of the widely used neurological examination Volume 9 Issue 2 - 2017 OK sign, which by itself tests the anterior interosseous motor branch of the median nerve. However, the OK sign has the potential to be incorporated into an examination technique which tests several nerves simultaneously. The OK sign would continue to test the anterior interosseous nerve, whilst a simultaneous wrist extension 1 additionally tests the radial nerve, metacarpophalangeal joint extension tests the Arthroplasty Fellow, Department of Trauma and Orthopaedic, Royal Liverpool University Hospital, UK 2 nerve. This ensemble of manoeuvers has the ability to succinctly test the majority of Senior House Officer, Department of Trauma and Orthopaedic, Royal Liverpool University Hospital, UK motorposterior nerves interosseous of the hand nerve, in a and single abduction smooth ofset the of thirdmovements. to fifth digitsAs this tests multi-motor the ulna 3Orthopaedic Consultant, Department of Trauma and neurological test is a progression of the OK sign, the development has been called the Orthopaedic, Warrington and Halton Hospitals NHS ‘Extended OK’ sign; EOK. Foundation Trust, UK Keywords: Physical examination; OK sign; Extended OK sign; EOK; Medial nerve; *Corresponding author: Fabienne Marie-Louise Robertson, Radial nerve; Ulna nerve; Motor innervation; Hand and Orthopaedic, Royal Liverpool University Hospital, PrescotBA, MBBS, St, MPH,Liverpool, Senior L69 House 3GA, Officer, UK, Email: Department of Trauma Received: July 26, 2017 | Published: October 20, 2017 Abbreviations: LOAF: Lumbricals, Opponens Pollicis, Abductor Therefore, although investigations may appear to overshadow Pollicis Brevis, and Flexor Pollicis Brevis; EOK: Extended OK; physical examinations, in reality their utility remains essential in MCPJ: Metacarpophalangeal Joint; PIPJ: Proximal Interphalangeal diagnostic practice. Therefore progress and the development of Joint; DIPJ: Distal Interphalangeal Joint new and improved techniques should be encouraged and pursued. Introduction Anatomy Review A neurological examination of the upper limb can be grossly assessed through hand examination. Orthopaedic examination the radiocarpal joint, and is composed of 27 bones, 14 of which techniques illicit signs which inform the clinician about the areThe phalanges, hand is 5 defined metacarpal as the bones, portion and of 8 thecarpal upper bones. limb distal to integrity of motor and sensory nerves, as well as musculoskeletal Intrinsic and extrinsic muscles of the hand are responsible function. for the wide range of broad and intricate movements. The In general, the advent of investigations has greatly challenged extrinsic muscles originate from the forearm whilst the intrinsic the perceived need for physical examinations [1]. However, muscles originate and terminate within the compartment of the modern thought is that history taking, physical examinations and hand. Intrinsic muscles of the hand include: thenar, hypothenar, investigations now form one sequential diagnostic entity, where interosseous muscles (four dorsal, and three volar), and the one informs the other [1,2]. A study by Peterson et al. [3], echoed lumbricals. The thenar eminence is found on the radial side of the palm, and is made up of three muscles: The abductor pollicis of diagnosing and found that, in 76% of patients, history led the doctorby Roshan to the[4], correctquantified diagnosis the relative and thatutility physical of each examination component isbrevis deep superficially, to the abductor which pollicis causes longus thumb and abduction, facilitates flexor opposition pollicis diagnosis [3,4]. ofbrevis the thumb.which causes The hypothenar thumb flexion, eminence and opponens lies on the pollicis ulna side which of and investigations then served to increase confidence in that the palm and is made up of three muscles: Abductor digiti minimi, History taking guides physical examinations which in turn determines which investigations would best aid in further analysis opponens digiti minimi. Palmaris brevis is sometimes considered of the patient’s presentation [5]. Using physical examination also toflexor be partdigiti of minimi the hypothenar, which causes however flexion it isof so the thin fifth it cannotdigit, and be prevents waste of needless investigations [5]. distinguished from the three hypothenar muscles deep. Due to the nature of orthopaedics it is possible to readily All hand muscles are innervated by three main nerves: Radial, illicit signs from the musculoskeletal system, and therefore ulna, and median. These branch out from the brachial plexus, physical examination skills are essential. Neurological upper limb which extends from the C5 to T1 spinal nerves. examination reproducibility were determined to be moderate to excellent, and therefore demonstrated important diagnostic benefits [6]. Submit Manuscript | http://medcraveonline.com MOJ Orthop Rheumatol 2017, 9(2): 00353 Copyright: Physical Examination: Extended OK Sign ©2017 Mohammed et al. 2/3 The radial nerve innervates the posterior compartment of the To summarise, the motor functions of the hand are controlled by arm, namely the medial and lateral heads of the triceps brachii, three main nerves: The radial nerve causes extension of the wrist and the posterior osteofascial compartment of the forearm, and digits. Whilst the median nerve is responsible for abduction including brachioradialis, aconeus, extensor carpi radialis longus. former becomes the posterior interosseous nerve, whilst the extension,and flexion and of the third thumb, and fourthopposition, proximal and firstinterphalangeal and second jointdigit latterIt then provides divides sensoryinto deep information and superficial to the branches,dorsum of where the hand. the metacarpophalangeal flexion and interphalangeal flexion and The deep branch becomes the posterior interosseous nerve after the supinator and innervates the extensor muscles of the hand interphalangealflexion. Finally, the joint ulnar extension, nerve is associatedand adduction with andthumb abduction adduction of and wrist as well as abductor pollicis longus. and flexion, third and fourth metacarpophalangeal flexion and The median nerve enters the upper limb from the axilla past Thefirst to Extendedfourth digits. OK Sign the inferior border of teres minor, then descends along with the brachial artery, starting laterally then crossing anteriorly to lie A common test used in clinical practice is the OK sign which medial to the artery, on the medial side of the arm between the biceps brachii and brachialis. The nerve then passes anteriorly tests the anterior interosseous nerve. In this study we propose an over the medial epicondyle into the cubital fossa medially, then Extendedgrossly verifies OK (EOK) the integritysign which of builds the median upon thenerve, traditional and specifically OK sign, continues into the forearm between the two heads of pronator jointsand subsequently (MCPJ), extended involves proximal the following: interphalangeal OK sign (flexed joint (PIPJ),index, teres, then between c, and finally emerges between the flexor extendedflexed thumb), distal extendedinterphalangeal wrist, jointextended (DIPJ) metacarpophalangeal of the 3rd, 4th and 5th digitorum superficialis and flexor pollicis longus. Starting digits, and abducted 3rd, 4th and 5th digits (Figure 1). Justproximally distal tothe the median lateral nerveepicondyle, innervates the median pronator nerve teres, gives flexor off carpi radialis, palmaris longus, and flexor digitorum superficialis. thirdthe anterior digits, andinterosseous pronator nerve quadratus. which Finally,innervates the flexormedial pollicis nerve passeslongus, throughflexor digitorum the carpal profundustunnel on thefor volar the lateralaspect ofsecond the wrist, and and sensory branches: The recurrent branch provides motor innervationdeep to the to flexor the muscles retinaculum, of the andthenar then compartment, divides into and motor the digital cutaneous nerve divides into the common and proper palmar digital branches which provide sensation to lateral palmar third digits including the lateral aspect of the fourth digit. Finally theaspect recurrent of the hand nerve and is theresponsible dorsum offor the the fingertips motor innervation of the first toof the thenar muscles (Opponens pollicis, Abductor pollicis brevis Figures 1: Physical Examination: Extended OK Sign-OK Sign, Extension Wrist and 3rd -5th Digits, Abduction of 3rd-5th Digits – Dorsal and Lateral Views. interphalangealand Flexor pollicis joints. brevis) All four and of the these first muscles and second innervated Lumbricals by the which flex the metacarpophalangeal joint and extends the recurrent nerve are known as the LOAF muscles. As previously mentioned, motor innervation of hand muscles The ulnar nerve is derived from the C8 to T1 nerves of the is supplied by the radial, ulna, median nerves. In addition to the brachial plexus. The nerve then descends posteromedially down initial OK sign, which tests the anterior interosseous branch of the the humerus and passes behind the medial epicondyle (cubital median nerve, wrist extension then tests the integrity of the radial tunnel) after which it enters the anterior compartment of the forearm. As the nerve descends, alongside and inferior to the posteriornerve, digit interosseous extension reflects nerve function, the integrity and