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Case Study
The patient is a 21-year-old male who has suffered a hand injury whilst playing a game of football on the weekend. He ran in for a contested mark when the ball forcefully contacted the tip of his middle finger causing forced flexion. The patient appears to have an acute case of “mallet finger,” affecting the extensor tendon in his hand.

The normal range of motion of the distal interphalangeal joint produces extension and flexion between 0 – 80 degrees. The patient’s finger is currently flexed at 45 degrees at the distal interphalangeal joint. He demonstrates the inability to complete full extension of the distal phalanx.

The patient would like to be able to return to football as quickly as possible and still be able to complete daily activities at home and at work as a plumber.

* Anatomy and Pathology
Orthotic treatment of mallet finger can only be successfully achieved if the intricate anatomy of the extensor mechanism of the hand and corresponding pathology are understood in conjunction with each other. Below explores the anatomy of the hand and details of the mallet finger injury. Mallet finger is classified as ‘loss of continuity of distal insertion of extensor tendon at the finger tip’ (Bailey and O’Brien, 2011, p.191). Combs (2000) stated that the injury might include a tear or rupture in the tendon or an avulsion of bony fragment from the distal phalanx. The mechanism of injury is important, as there are several causes of extensor tendon injuries as agreed with Griffin, Hindocha, Jordan and Saleh (2012) therefore various levels of severity and methods treatment need to be determined. Common causes include ball sports and work and home accidents as Alexandru, Georgescu, Capota and Matei (2013) considered. This male patient acquired his injury through a football forcefully contacting the distal phalanx, causing sudden flexion. Additionally, Griffin, Hindocha, Jordan and Saleh (2012), state that damage to the extensor tendon may arise from clean or contaminated bites/lacerations, crush injuries to the tip of the distal phalanx. There are various severities of mallet finger injury, which Bailey and O’Brien (2011), Alexandru, Georgescu, Capota and Matei (2013), Griffin, Hindocha, Jordan and Saleh (2012) and North Austin Sports Medicine (2014) agree that, the Doyle’s (1993) classification of mallet finger is considered a valid method to use. In the case of this patient he is classified as Doyle (1993) type 1 – extensor tendon avulsion from distal phalanx.

In order to classify mallet finger, anatomy of the extensor mechanism must be comprehended. The anatomy of the extensors of the forearm/hand is very complex in comparison to the flexors as agreed by Combs (2000) and Newport and Tucker (2005). These sources harmonize that the extensor tendons are thinner/less extensive and the longitudinal layout of collagen creates a “lack of collagen-bundle linkage” (Griffin, Hindocha, Jordan and Saleh, 2012 p.36), hence a greater weakness. The extensor tendon originates in the forearm diving into four muscle bellies as stated by Griffin, Hindocha, Jordan and Saleh (2012), passing through the wrist compartment dorsally, where they lie superficially over the dorsum of the hand forming into the extensor expansion or “hood” (which conjoin to tendons of the intrinsic muscles) as mentioned by Combs (2000). Trifurcation of the extensor tendon occurs at the proximal interphalangeal joint (PIPJ), establishing a central band accompanied by two lateral bands that insert at the dorsal base of the distal phalanx. It is at this point where an avulsion, laceration or rupture of the dorsal and superficial lateral bands occurs at its insertion, disallowing full, passive extension of the distal interphalangeal joint (DIPJ). In the case of this patient, an avulsion of the extensor tendon, of the third digit has occurred. Combs (2000) and Agur, Dalley and Moore (2010) present the innervation of the forearm/hand: the medial nerve innervates the middle finger, radial nerve innervates the extensor muscles and the ulnar and median nerve innervates the intrinsics and interossei. Sensory nerves are in abundance in the fingertip, hence why pain is often felt with mallet finger Cannon (2003). Combs (2000) continued that the extensor mechanism has responsibility to extend 3 joints in comparison to the flexors; hence the complexity and crucial need for prompt response post injury to achieve optimal healing results. The intricacy of the extensors has such variation in function/structure along its length, creating variances in injuries, hence the creation of a classification system, dividing the hand into eight zones as mentioned by Hooper and Watts (2004). The extensors of the hands are classified through zones 1, 3, 5 and 7, with mallet injury as being a zone 1 injury.

* Orthotic Treatment Options and Comparisons
According to Finical and Johnson (2000) mallet finger is simple to diagnose due to the inability of the patient to passively complete full extension. However, to aid diagnosis Dodds and Oetgen (2007), Finical and Johnson (2000), Combs (2000) and Capota, Georgescu and Matei (2013) believe classifying the severity/type of injury via radiographs are necessary before implementing any kind of treatment. Prompt response and early detection of the extensor lag is vital to protect against chronic mallet finger which may result in an additional “swan neck deformity” (Capota, Georgescu and Matei, 2013, p.46) affecting the PIPJ due to an imbalance in the extensor mechanism. Early detected injuries of the extensor tendon in the DIPJ, which present as closed, and occur within 1/3 of the articular surface, can be easily treated via conservative, orthotic management according to Dodds and Oetgen (2013). Surgery, using Kirschner wires to immobilize the DIPJ, is another method of managing mallet finger – however, is generally used in more severe cases such as open wounds, crush wounds, or when more than one third of the articular surface is affected as Capota, Georgescu and Matei (2013) suggests. However, in the case of this patient, orthotic management is sufficient for optimal and adequate healing of the injury.

Orthotic management of mallet finger is commonly achieved via a prefabricated stack splint, dorsal aluminum- foam splint or a custom made thermoplastic orthosis as compared by Bailey and O’Brien (2011) and agreed by Finical and Johnson (2000). The affected mallet finger should be immobilized in a fully extended position as suggested by Finical and Johnson (2000) and Dodds and Oetgen (2007) to reduce tension of the extensor tendon and allow healing to occur. However most recent research proves that slight hyperextension (5°-10°) when splinting is the most “preferred method,”(Capota, Georgescu and Matei, 2013 pg. 351) provided that care is taken to “prevent dorsal skin ischemia,” (Dodds and Oetgen, 2007 pg. 99-100) when placed in this position. The DIPJ should be individually immobilized, allowing all other joints (PIPJ) to have full range of motion, to reduce stiffness and prevent new morbidities arising in the effected finger as found by Dodds and Oetgen (2007).

Time spent wearing the orthosis should also protect against potential morbidities arising in the finger. Pike et al. (2010), Finical and Johnson (2000), Canon (2003), Combs (2000) and Brady, Hersh, Keats and Perron (2002) provide a recommended splinting time range of 4 – 8 weeks followed by night splinting for an additional two weeks. Within this splinting time, full immobilization should not continue beyond 4 weeks as it may cause “chronic stiffness and joint capsular scarring,” whereas, implementing “early motion prevents adhesions,” from occurring.(Dodds and Oetgen 2008, pg. 97). Gradual increases of motion should be included in the rehabilitation progress to regain strength and prevent stiffness in the injured joint. Canon (2003) proved that, provided adequate healing, active range of motion exercises shall commence at approximately 3 weeks, and followed by passive exercises at 4 -6 weeks, in conjunction with night splinting. Generally, patients heal with adequate range of motion, however, most, at best, have a remaining 5°-10° extensor lag as shown in Cannon (2000). The healing of patients is a crucial outcome that needs to be measured, however, Asghar and Helm (2013), mentioned that there was no standard way to achieve this for mallet finger. Conversely, this article appears of poor quality as (Capota, Georgescu and Matei, 2013 pg. 353) measured healing of patients via ”Crawford’s evaluation criteria,” measuring range of motion against pain, with most patients considered as “excellent” or “good” after orthotic treatment. Thus proving that splints used for mallet finger, placed in the right position accomplishes effective results.

A Cochrane Review, updated in 2008, investigated the validity of separate orthotic treatments of mallet finger and demonstrated that there is “not enough evidence to show which is the best way to treat mallet finger injury” (Handoll and Vaghela, 2008 pg. 2). Despite the fact this review consisted of 4 trials only, all of which were all “methodologically flawed” (Handoll and Vaghela, 2008 pg. 1), Bailey and O’Brien’s (2011) more recent study proved equivalent, in that, no statistically significant difference was found when treating mallet finger with the three recommended types of orthotics – aluminum/foam splint, prefabricated stack splint and custom-made thermoplastic. Ideally, when complied with, each treatment proves valid, however a custom made thermoplastic splint proved more durable and “robust,” (Handoll and Vaghela, 2008) as suggested, by the Cochrane Review, hence less complications or failure, leading to an increased compliance, therefore rapid results and improved efficiency of healing time of the injury.

* Conclusion
In the case of this 21 year old male patient’s injury, he has suffered a zone 1 – type 1, Doyle (1993), closed avulsion of the extensor tendon from it’s insertion on the distal phalanx, within one third of the articular surface. Based upon the literature, a custom-made low temperature thermoplastic orthosis will be the selected treatment for him. Surgery is deemed unnecessary. Duration of orthotic treatment will consist of 6 weeks of splinting and 2 weeks of night splinting, beginning range of motion exercises at 4 weeks. An improved range of motion, reduced extensor lag and achieving patient goals is aimed to be achieved post treatment.

* Search Strategy
Databases used for this research were Medline, Cochrane and Google Scholar. Key words use to conduct the research were: mallet finger, dropped finger, distal interphalangeal injury, orthosis, orthotic management, treatment, rehabilitation, anatomy, pathology. Evaluation of these papers proved the sources were valid, some were aged however, still proved relevant and valid and their use in this project was justified. There were numerous materials to use for this common pathology, however difficulty was found when searching for full texts.

Functional Aims and Goals
The functional aims of providing a custom made low temperature thermoplastic stack splint to the patient ultimately allow optimal healing and ability to achieve daily activities of living, whilst enabling correction of the injury.

The design of the stack orthosis enables movement at all joints except the affected DIPJ. This enables majority of tasks to still be accomplished, as it is only a small, distal joint affected. The patient will still be able to work in his occupation as a plumber completing simple tasks, however, it is best he not play football and avoid high impact during the duration of healing. The splint should be molded onto the patient in approximately 5 degrees hyperextension. This position relaxes the tendons, reducing stresses and allows for optimal hearing and minimal extensor lag once splinting is completed. Night splinting will continue after the duration of permanent splinting to continue the healing process and prevent relapse. All these features of the thermoplastic orthosis will allow return of normal function and range of motion to the most ideal as possible.

The orthosis is easily removable for the patient so they can maintain hygiene throughout the healing process. Ways of cleaning should be taught to the patient due to the importance of keeping the position of the DIPJ in 5degrees hyperextension (at the least extension) at all times to reduce extensor lag.

The Plaster of Paris (POP) cast would be used in the initial days post injury. It would be used whilst edema is present, and or, until an orthotist is available. The POP splint achieves the same functional aims as the low temperature thermoplastic however, is less durable and cannot get wet, therefore it being less reliable and only valid for short-term use.

Design
The design chosen for the orthosis was a custom-made thermoplastic stack splint. The distal interphalangeal joint (DIPJ) should be positioned in slight hyperextension, no greater than 5 degrees hyperextension. This will allow the ligaments to heal and relieve the stress on the extensor tendon.

A 3-point force system is applied; -	Force 1 is applied in a superior direction on the volar side of the finger, at the most distal point on the tip of the finger -	Force 2 is applied in an inferior direction on the dorsal side of the finger, just proximal to the distal interphalangeal joint -	Force 3 is applied in a superior direction on the volar side of the finger, just distal to the proximal interphalangeal joint

Figure 3 below demonstrates the 3-point force system in the sagittal plane. It cannot be drawn in any other plane as the force is only really directly applied in the sagittal view.



The distal end of the orthosis, between the DIPJ and tip of the finger should cover the volar surface and leave the dorsal surface exposed, without covering the fingertip. The orthosis should cover the full circumference of the finger between the DIPJ and PIPJ. The full circumferential covering allows for strength and support due to the small lever arms in the finger orthosis. Immobilisation of the DIPJ should be apparent, whilst allowing full movement at the PIPJ.

The full circumference of the orthosis creates suspension. A second orthosis was made where the surface between PIPJ and DIPJ only covered half the circumference and was suspended via a Velcro strap. The area proved to be to small and the strap did not suspend well and a 3-point force system was unsuccessful in that design.

Manufacturing process
Step 1: Gather material needed, these include (as pictured below): -	A piece of paper for a stencil -	Sharp scissors -	Pen -	Tape measure -	Ruler -	Towel -	Fry pan filled with water -	Low temperature thermoplastic -	Curved scissors



Step 2: - Fill the fry pan with water. - Turn the fry pan on to allow it to heat up



Step 3: Begin creating stencil for the splint:

-Place the patients hand onto the piece of paper

-Trace the client’s affected finger, be sure to keep the pen vertical and perpendicular to paper whilst tracing

- Once the finger is outline is complete, mark on each side the position of the DIPJ and PIPJ



Step 4: -measure the clients circumference of their finger between the DIPJ and PIPJ

Step 5: -	As displayed in the picture, using the circumference measurement, draw a line across the DIPJ joint, with the middle of the finger being the middle of the circumference measurement -	Repeat the same, now drawing a line just under the PIPJ (the extra length to allow for rolling of the edges later on) -	Join both DIPJ and PIPJ lines with vertical lines on each end -	Now trace around the finger tip, leaving approximately a 2mm gap



Step 6: -	Cut out stencil -	Trace stencil onto sheet of thermoplastic -	Cut away large edges around stencil



Step 7: -	Place thermoplastic into the hot water in the fry pan -	Keep in water until the plastic starts to become flexible (test by pushing down gently on the plastic with scissors while it’s in the water

Step 8: -	Remove thermoplastic from the heat -	Dab dry once on each side with a towel -	Cut out the stencil (cut in one direction, turn the thermoplastic as you cut, this makes it easier to cut the plastic)



Step 9: -Return the thermoplastic back to the heated water until it has become flexible again -Remove from water, dab dry and roll the bottom edge up approximately 3-5mm -Rolling this edge will allow smooth trimlines and ability for the finger to move at the PIPJ



Step 10: -	Place patient in a chair in a comfortable position -	Lay their hand flat either on the arm of the chair or a table -	Place the rolled edge thermoplastic into the water until flexible -	Dab dry and quickly move to the patient to begin molding on the plastic



Step 11: -	Place the piece of plastic under the finger, applying to the volar surface first

-	Make sure the rolled edge is facing outward to the finger

-	Fold the flaps up and around the whole circumference of the finger, pushing the ends very tightly together to create a seal

-	Mold the fingertip section up and around so it comes approximately halfway up the distal end of the finger, without covering the nail – keep the DIPJ in 5 degrees hyperextension, holding this position until it is securely moulded

-	Before the plastic dries, using curved scissors, cut the excess off the dorsal surface of the splint



Step 12: - Dip any edges that need smoothing out into the water and smooth over with finger - The orthosis should be completed and look similar to below



Critique of fit
This client is a 21 year old male from Bundoora who has presented with pain and swelling in his right middle finger (at the distal phalanx). He works full time as a commercial plumber and plays football on the weekends and is hoping he can return to these activities as soon as possible.

The patient reported pain at his fingertip after going for a mark during football on the weekend. He claimed that he thought he ‘jarred’ his finger so he taped it and continued playing the remainder of the game. The patient cannot actively extend his distal phalanx. He currently is reporting pain and oedema is present at the point of injury. The injury affects his work with things such as hammering and reduces his ability in football. His goal is to get back to his normal activities as quickly as possible.

A physical assessment was completed and revealed that range of motion (ROM) appeared normal in the wrist, all other fingers and in the other joints of the affected finger; the proximal interphalangeal joint and metacarpal joint. Passive, active and resisted ROM were achieved and within normal ranges. The affected right distal interphalangeal joint was unable to actively extend. Passive ROM was achieved but the patient felt pain. Resisted movement was incomplete and a oxford muscle grading score of zero was given.

Considering the above results, a diagnosis of mallet finger was given as active extension was unachieved by the patient.

The goal of orthotic management is to achieve the client goals, allow return to full ROM and heal the injury. The client wishes to return his physically demanding occupation and his weekend football as soon as possible with the best results possible. Healing of the tendon and avulsed bony fragment needs to be achieved in order to return full ROM for the patient.

In order to achieve these goals a custom made thermoplastic stack splint has been developed. This splint will disallow flexion at the distal interphalangeal joint (DIPJ) and place the fingertip into slight (5 degrees) of hyperextension in order for the extensor tendon and bony fragment to heal. The splint will allow full ROM at the proximal phalangeal joint (PIPJ) and surrounding joints. The fingernail will remain uncovered and the area between the DIPJ and PIPJ will have full circumferential covered for extra support as the small area affects will have a small lever arm and needs more care.

The device made meets most technical design requirements. ROM has been allowed at the PIPJ and hyperextension with denied flexion at the DIPJ is achieved. The proximal trimline is smooth, folded well and lies correctly on the finger. The posterior trimlines around the fingernail are smooth and however not completely stright around the distal area of the fingertip. Increased care when cutting the thermoplastic would help reduce this. The splint fits the customer very well and achieves/disallows the correct movements. The 3point force system is applied and the full circumferential area allows for extra support, as the lever arm of the affected area is only small. The orthosis meets all orthotic goals and will allow optimal healing of the affected area.



Outcome measures
Outcome measures help to evaluate the severity of a condition and determine progress to a set program (e.g. orthotic treatment/process). Outcome measures used for mallet finger are measuring ROM, testing muscle grading; based on the Oxford Muscle Grading system (Open Physio, 2013) and the degree of extensor lag.

ROM Testing: This testing allows the clinician to see whether or not the patient has range of motion within the normal values or if an injury or condition affects the motion. Active, passive and resisted muscle testing shall occur. Active ROM testing is achieved by the patient moving there own joints, passive ROM occurs when the clinician physically moves the patient’s joints and resisted is when the patient actively moves there the clinician give own joint against resistance. Any ranges, which appear to be out of normal ranges, should be measured by a goniometer.

Muscle Grading: Testing the muscles ability is achieved via asking the patient to move or contract a certain muscle. Start working the way down the Oxford Grading Scale of 5 and the accompanying criteria. If the level 5 is able to be completed stop there, if not, continue until a score has been reached.

Extensor Lag: The extensor lag of the DIPJ is measured via a goniometer. Allow the patient to relax their finger, place the center of the goniometer at the DIPJ itself, the stationary arm following the longitude of the finger in a proximal direction and the moving arm following the longitudinal axis of the distal phalanx. Observe and record measurement.

The 21-year-old male patient was measured on initial consultation, 3 weeks of splinting and post treatment after 6 weeks of treatment for all the above tests. The client reported the following results:

Results

Test:	                              Initial - 	3 Weeks -    	6 Weeks

ROM PIPJ	                         90°	          100°	            100°

ROM DIPJ	                   0°	            40°	              77°

Muscle grading PIPJ	      4	              5                 	5

Muscle grading DIPJ           0	              4	                        5

Extensor Lag	            30°	            15°	                3°

The results of these outcome measures have proved that orthotic treatment via a thermoplastic stack splint with ROM exercises was successful as the finger and affected DIPJ has returned to near normal function. A slight extensor lag appears to be normal in most cases of avulsed bone/tendon mallet finger injuries.

Reference List
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Asghar, M and Helm, R. H. (2013). Central Slip Tenotomy for Chronic Mallet Finger. The Surgeon, Journ of Royal Colleges of Surgeons Edinburgh and Ireland, 13, 264-266. Retrieved from     http://www.sciencedirect.com/science/article/pii/S1479666X13000656?via=ihub

Bailey, J. M., O’Brien, L. J. (2011). Single Blind, Prospective, Randomized Controlled Trial Comparing Dorsal Aluminum and Custom Thermoplastic Splints to Stack Splint for Acute Mallet Finger. American Congress of Rehabilitation Medicine, 92, 191 -198. Retrieved from http://www.archives-pmr.org/article/S0003-9993(10)00867-1/fulltext

Brady, W. J., Hersh, R. E., Keats, T. E and Perron, A. D. (2002). Orthopedic Pitfalls in the Emergency Department: Closed Tendon Injuries of the Hand. American Journal of American Medicine, 19(1), 76 – 81. Doi:10.1053/ajem.2001.20038

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Capota, I. M. V., Georgescu, A. V. and Matei, I. R. G. (2013). A new surgical treatment for mallet finger deformity: Deepithelialised pedicled skin flap technique. Injury, Int. J. Care Injured, 44, 351–355.

Combs, J. A. (2000). It’s Not “Just A Finger”. Journal of Athletic Training, 35(2), 168-178. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1323414/pdf/jathtrain00002-0050.pdf

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Doyle, J. R., (1993). Extensor Tendons – acute injuries. New York: Churchill Livingstone

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