Physical Examination: Extended OK Sign

Home , Hypothenar eminence, Muscles of the hand, Ulnar canal

MOJ Orthopedics & Rheumatology

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 part digiti of minimi the hypothenar, which causes however flexion it is of so the thin fifth it cannot digit, 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].

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 sensory into 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, joint extended (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 to the 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, through flexor digitorumthe carpal profundustunnel on the for volar the lateralaspect of second 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 digitof the abduction radial nerve reveals and th and 5th digits. Before theextensors, function whilst of the ulnar metacarpophalangeal nerve. extension reflects the ulnar artery, it supplies flexor carpi ulnaris and the medial half entering the palm of the hand, through the ulnar canal (Guyon’s The suggested order of examination is as follows: canal),of flexor the digitorum nerve divides profundus into three for the branches: 4 Muscular, palmar and dorsal branches of the ulnar nerve. Once the ulna nerve passes a. OK sign (1st and 2nd

b. Wrist extension digit flexion) formerover the innervates superficial palmaris retinaculum brevis it gives and offprovides two branches, sensation namely over c. Digit extension (3rd 4th 5th MCPJ, PIPJ, DIPJ) the superficialpalmar aspect and ofdeep the branches third and of fourth the ulnar digits, nerve, and wherethe latter the d. Digit abduction (3rd 4th 5th digits). innervates adductor pollicis longus, third and fourth lumbricals, With the Extended OK sign, in one composite set of movements, minimi, abductor minimi and opponens digiti minimi). upper limb motor nerve function is primarily tested. interosseous muscles, and the hypothenar muscles (flexor digiti

Citation: Mohammed AA, Robertson FML, Shah N (2017) Physical Examination: Extended OK Sign. MOJ Orthop Rheumatol 9(2): 00353. DOI: 10.15406/mojor.2017.09.00353 Copyright: Physical Examination: Extended OK Sign ©2017 Mohammed et al. 3/3

Discussion screening test for the motor nerves of the hand. This test is sensitive for the majority of the three main hand motor nerves and would be useful in areas where time and/or expertise are limited. abductorSpecifically, pollicis extension longus. of Therefore the wrist andthe digitsintegrity tests of the the majority radial nerveof the is extensor tested up tendons to the level though of the does wrist not and specifically then more testdistally the At a time where investigations are the focus of innovation, it with the digits, but not medial innervation to the thumb. An extra examination for abductor pollicis longus would be needed to to develop physical examination as an essential diagnostic tool in completely test the radial nerve. patientis important management. to highlight The the Extended continued OK significance sign is a quick and screeningnecessity test for the radial, median, and ulna nerves which can be easily applied and taught. The OK sign specifically tests for the anterior interosseous I put it forward that, by adding three sequential movements nerve which means it does not completely test for flexor digitorum to the widely used OK sign, namely wrist extension then superficialis, flexor digitorum profundus nor the LOAF muscles. metacarpophalangeal joint extension, followed by digit extension digitorumMore specific profundus tests would as well be as needed the recurrent to complete motor examination branch for then abduction, the Extended OK sign is a logical clinical theof theLOAF median muscles. nerve for flexor digitorum superficialis, flexor progression which has the ability to provide a quick and relatively simple general motor innervation screening test of the hand. Abduction of the digits is innervated by the deep ulna nerve which is a continuation of the ulna nerve. However, the function of Acknowledgement the hypothenar muscles, medial lumbricals and adductor pollicis None to declare. the ulna nerve within the hand would need to be carried out to completeare not specifically the examination tested andof the so motorfurther ulna tests nerve. for the branches of Statement of Funding The EOK examination is a screening tool and does not have the pretense of testing every digital branch of all three nerves and is This article received no specific grant from any funding agency not meant to provide a complete neurological assessment. Rather Conflictin the public, of commercial, Interest or not-for-profit sectors. will then require further examination and investigation. it has the ability to succinctly illicit potential motor deficits which General tests are taught to screen for possible hand injuries: StatementThe authors of declareHuman that and they Animal have no Ethics conflict of interest. Extension of the wrist and digits is taught to test the radial nerve, This article does not contain any studies with human or animal digit abduction as an indicator of ulna nerve function, and an subjects. intact OK sign demonstrates integrity of the median nerve. This EOK sign combines these basic principles into one succinct test, References which in one move is able to generally test the motor innervation of the hand and reveal whether there exists a motor neurological 1. Abraham V, Blake C, Jerome PK, Meghan R, John PAI (2015) Inadequacies of Physical Examination as a Cause of Medical Errors and Adverse Events: A Collection of Vignettes. Am J Med 128(12): deficitAt a requiring time when further clinicians evaluation. are increasingly specialized and the 1322-1324.e3. role of non-doctor staff is developing, there is a need to establish 2. Schultz MA, Doty M (2016) Why the History and Physical sensitive tests which allow non-hand surgeons to screen patients Examination Still Matter. 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Muhrer JC (2014) The Importance of the History and Physical in cases, and as an initial assessment of hand motor innervation. If Diagnosis. Nurse Pract 39(4): 30-35. 6. Jepson JR, Laursen LH, Hagert CG, Kreiner S, Larsen AI (2006) would be warranted. Diagnostic Accuracy of the Neurological Upper Limb Examination I: an issue is identified by the EOK sign then further specific tests Inter-Rater Reproducibility of Selected Findings and Patterns. BMC Conclusion Neurology 6: 8. The Extended OK sign is a straight forward evolution of the traditional OK sign offering an effective and efficient neurological

Citation: Mohammed AA, Robertson FML, Shah N (2017) Physical Examination: Extended OK Sign. MOJ Orthop Rheumatol 9(2): 00353. DOI: 10.15406/mojor.2017.09.00353