Upper Limb Orthotics/Rupture of the Finger Flexor Annular Pulley A2

Abstract here...

Case Study Description
A healthy 28 year old woman experiences a ‘pop’ sound in the ring finger of her right hand on a rock climbing adventure. She is a highly experienced climber who reports no previous serious finger injuries. She ceases climbing immediately and seeks treatment on the same day. An MRI shows that she has a complete rupture of the finger flexor annular pulley A2. The treating doctor classifies the injury as Grade 3, and refers her to an orthotist for a thermoplastic splint. The patient aims to be able to return to rock climbing in time for a competition in two months.

Rupture of the Finger Flexor Annular Pulley
The phalanges of the hand are capable of many precision and strength grips. For rock climbers the ability to use the hands to grip small ledges and nooks is essential and can require them to adopt unusual grip positions. One of the most common injuries for rock climbers is a rupture or tear to one or more of the annular pulleys of the fingers (V. Schöffl, Hochholzer, Winkelmann, & Strecker, 2003). Repair of these injuries can be either surgical or conservative and depends upon what pulley is damaged and the degree of damage. Little evidence is available regarding the recommended orthotic management for this condition; however the epidemiological data, role of the annular pulleys in finger flexion and mechanism of injury are well documented.

Epidemiology
The occurrence of injuries to the annular pulleys of the fingers was first documented in the 1980’s and the first substantial piece of research was published in the early 90’s, in accordance with an increase in the popularity of the rock climbing sport (V. Schöffl et al., 2003). A prospective study over four years from 1998 in Germany found that 40% of rock climbers with upper limb injuries had damaged their fingers, and half of these were ruptures or strains to the annular pulleys, making annular pulley injuries the most common upper limb grievance for rock climbers (V. Schöffl et al., 2003). A retrospective study of South African rock climbers in 1994 showed similar figures, with 44.3% of all rock climbing injuries -including trunk and lower extremities -being isolated to the hand (Holtzhausen & Noakes, 1996). A more recent study of rock climbers in the United Kingdom found 35% of upper limb injuries were to the fingers (Jones, Asghar, & Llewellyn, 2008), suggesting that the epidemiology of rock climbing injuries is similar in various geographical locations. Studies on the occurrence of pulley injuries in non-climbers have found their subjects in bowlers, professional baseball pitchers and people lifting heavy objects (Lourie, Hamby, Raasch, Chandler, & Porter, 2011; Patel, Schucany, Toye, & Ortinau, 2012; V. Schöffl et al., 2003).

Role of Annular Pulleys in Finger Flexion
The individual phalanges of the hand have the capability of flexing at three joints: the metacarpal-phalangeal, the proximal inter-phalangeal (PIP) and the distal inter-phalangeal (DIP). A number of muscles are involved in this process, but in order to prevent them from bowstringing a digital flexor sheath is needed. It is comprised of two constituents- a membranous component and a pulley component, of which the pulley component is relevant to the rock climbing injury being investigated. The pulleys are composed of fibrous tissues which wrap around the flexor tendons, with the membranous component of the sheath being visible between the pulleys (Doyle, 2001). There are five annular pulleys and three cruciform pulleys, numbered from proximal to distal. The annular pulley A2 is positioned between the metacarpal-phalangeal joint and the PIP joint. The role of the annular pulleys is to prevent bowstringing and allow for force transferral (Schoffl, Einwag, Strecker, & Schoffl, 2006).

Mechanism of Injury
The mechanism of injury has been well investigated in rock climbers. The crimp grip is one of two common grips used by rock climbers, usually when contact between the fingers and a small ledge or rock needs to be at its closest (Marco, Sharkey, Smith, & Zissimos, 1998). The grip involves the DIP joint being hyper-extended and the PIP joint being flexed to 90-100° (Crowley, 2012; Marco et al., 1998). It allows for the maximum amount of power to be generated by flexor digitorum profundus (FDP) and for maximum force transferral over the A4 and A2 pulleys (Crowley, 2012; Holtzhausen & Noakes, 1996). There is some disagreement regarding the maximum possible load upon an A2 before pulley rupture occurs when using the crimp grip. It has been calculated at 375N (Tang, 1994) to an estimation as high as 450N based upon a case study (Bollen, 1990). A more recent study suggested a figure of 400N, but conceded that the maximum force could be higher in experienced rock climbers (Schweizer, 2001).

An annular pulley injury typically occurs when a climber is in the crimp position and experiences a sudden loss of footing (Bollen, 1990) or when performing a difficult move (V. Schöffl et al., 2003). Eccentrically loading the annular pulleys is also associated with a higher rate of injury (I. Schöffl et al., 2009). This is due to the friction created between the FDP tendon and the pulley. However, the friction also increases the holding ability of the flexor muscles, so it can be an advantage to the climbers (I. Schöffl et al., 2009).

Grading System for Annular pulley Injuries
The diagnosis of annular pulley injuries is recommended to be carried out using an MRI or CT scan, or possibly an ultrasound (Kubiak, Klugman, & Bosco, 2006) though some research argues that ultrasonography is also highly reliable (Klauser et al., 2002). Once the injured pulley has been identified it can be classified based on its severity into four categories (V. Schöffl et al., 2003). The type of injury- strain or rupture- and its pulley number allow it to be defined as grade 1-4. For instance, a complete rupture of A2 is classified as Grade 3, but a partial rupture of A2 is Grade 2 (V. Schöffl et al., 2003). Table: Grading System and Treatment Options. Table adapted from Schloff et al (2003).

Recommended Treatment
Often at the onset of injury, an audible ‘pop’ is heard, notifying the climber that something is wrong with their finger (Holtzhausen & Noakes, 1996; Kubiak et al., 2006; V. Schöffl et al., 2003). It is recommended that they cease climbing immediately and seek treatment from a health professional, commonly a doctor or physiotherapist (Jones et al., 2008). A pulley injury that is not severe enough to be categorized as Grade 4 and operated upon is therefore best treated by conservative methods.

The use of anti-inflammatory drugs, immobilisation and elevation is recommended for acute injuries (V. Schöffl et al., 2003). After the removal of the immediate immobilization device, functional therapy should begin. When climbing, taping is recommended for the next 3-6 months as it can take this long for strength to return to normal in the pulley (V. Schöffl et al., 2003; Schoffl et al., 2006). A H type configuration of taping is the most effective as it decreases the tendon-bone distance (I. Schöffl, Einwag, Strecker, Hennig, & Schöffl, 2007).

Orthotic treatment options
Conservative management of annular pulley ruptures is recommended for grades 1-3, with buddy taping for 0-10 days for grades 1 and 2, and a soft cast ring or palmar thermoplastic splint for 14 days for grade 3 (V. Schöffl et al., 2003). The splint should be removed after 10-14 days so as to avoid the possibility of a flexion contracture developing. There is little evidence regarding the efficacy of various splint designs for the immobilization of the digit and it appears that the design of the thermoplastic splint is at the discretion of the treating health professional. The splint does need to completely immobilize the joint, and biomechanical research has suggested that a three or four-point force system is effective. The hand is best positioned with slight flexion of the metacarpal-phalangeal and PIP joints (Holtzhausen & Noakes, 1996).

The use of finger rings to prevent flexion/ extension is an alternative to the thermoplastic splint. Commonly found as pre-fabricated devices, the metal structure applies a three point force system to the finger that can be manipulated by the clinician using pliers. A metal ring specifically for A2 pulley injuries has been designed and is sold commercially. It works to prevent bowstringing of the flexor tendon and is also available in a hinged version for swollen or large PIP joints (SIRIS Ring Splints, 2014). This device would be useful when clinical bowstringing is an issue, but it does not immobilise the pulley for repair. No pre-fabricated device exists specifically to immobilise the A2 pulley, however a design similar to that used for PIP joint injuries would be sufficient, as it prevents flexion (Trulife, 2014, p. 26).

Comparison of orthotic treatment options
There have been no clinical studies published that compare the effectiveness of finger rings to thermoplastic splints for the immobilisation of the finger. Provided that the device achieves the orthotic aim of immobilisation, it would be suitable for a patient. The ring design has the added bonus of great cosmesis, however it is assumed that most doctors/physiotherapists or orthotists do not keep a prefabricated pulley ring or flexion prevention ring in stock and so would have to order one in for their patient. This of course would take delivery time and as the aim is to immobilise the joint immediately, a custom-made thermoplastic splint may be a faster and easier solution. Aside from this argument of convenience, there is no other supporting information for choosing one device over the other. There is however, a large body of research that has determined when surgery is a better option than conservative management of these injuries. Surgical treatment is recommended for grade 4 annular pulley injuries where there is involvement of two or more pulleys or damage to the lumbricalis muscle or ligament (V. Schöffl et al., 2003). Surgical reconstruction for all open pulley injuries was recommended for a time but research on the strength of surgically repaired versus conservatively managed injuries suggested no long term differences, except for grade 4 injuries (Schoffl et al., 2006). There is no current evidence on the outcomes for operative vs. non-operative measures (Kubiak et al., 2006), however one study on outcome measures found that five patients with grade four injuries who were treated conservatively regained full strength in their finger (Schoffl et al., 2006), suggesting that operative methods for grade four injuries are not always necessary. It is concluded that pulley injuries of grades 1-3 should be managed conservatively, unless there is a persistent strength deficit, and grade 4 injuries should be evaluated for surgical reconstruction (Schoffl et al., 2006).

Overview
Although injuries to the annular pulleys of the fingers are isolated to a very specific population, the impact of this injury upon a patient’s ability to undertake the sport they enjoy is detrimental to their wellbeing. Research into the epidemiology, role of the pulleys, mechanisms of injury, proposed grading systems and surgical methods for repair have provided useful information for climbers and clinicians. However, the absence of information on the efficacy of orthotic splints for immobilisation highlights a lack of evidence in the non-surgical treatment stream. A common splint design should be readily available for health professionals to access if they need to immobilise an annular pulley injury.

Appendix 1: Search Strategy
Databases searched: MEDLINE, Cochrane Library

Search Terms used:

-	Annular pulley, pulley, A2, rupture of pulley, flexor tendon

-	Finger orthos*, splint, thermoplastic splint, immoboli?*, phalang*, finger, hand

-	Repair, surgery, treatment

Functional Aims and Goals
The functional aim of this device is to immobolise the annular pulley A2, by restricting movement at the MCP and PIP joints. Complete immobolisation should allow the ruptured pulley to begin healing (Schloff, 2006). The device, however, should not impede movement of the wrist, thumb or DIP joint of the affected finger. The use of a device may also immobolise the next digit (in this case the 5th) to provide stability, but again the DIP joint of this adjacent finger should be free to move. If the patient cannot actively flex or extend their MCP or PIP joints, then the functional aims have been achieved.

The POP cast was a replica of the LTT device design. There is no current clinical research suggesting that a high-temp thermoplastic long-term device would be necessary for a pulley rupture, hence why the POP cast was the same as the LTT device. As such, the POP cast’s functional aims are the same as those for the LTT orthosis; to immobolise the pulley

Design
The design: a small hand orthosis that covers the 4th and 5th phalanges over the PIPJ and MCPJ. The design is similar to that of a boxer’s fracture splint but incorporating the height difference between the 4th and 5th is optional (may just be a straight line instead of a step) and without the severe flexion at the MCPJs. Coverage on the dorsal and volar aspects is simply to provide stability for the device.

Manufacturing process
In order to replicate this LTT Hand Orthoses, we recommend that you follow these steps.

1.Prepare the design and draw an outline of your patient’s hand on a piece of paper/chux/paper towel.

2.Copy the design onto the outline of your patient’s hand. Make allowances for smaller or larger hands. Try to be accurate, but its better to overestimate the amount of thermoplastic you will need than to underestimate.

15.Attach a strap at each of the rounded ends across the posterior of the hand.

16.Fit device to the patient and ensure straps are tight but comfortable.

Critique of fit
The patient is a 28-year-old female who injured her hand during a rock climbing exercise. The patient has no previous history of hand or wrist injuries.

Upon presentation to the clinic, the patient’s right hand had a swollen ring finger between the MCPJ and PIPJ. The patient reported a constant pain level of 2/10 but during grip that increased to 5/10. When the incident occurred two days prior, the patient immediately ceased climbing after hearing a ‘pop’ sound and proceeded to ice their hand.

Palpation of the injured finger revealed no loss of bone integrity. No bowstringing was visible. Flexing of the finger at both the MCPJ and PIPJ caused discomfort. The referring doctor had already ordered MRI’s and they revealed damage to the Finger Flexor Annular Pulley A2. The doctor rated this injury Grade 3 and recommended orthotic intervention.The patient stated that they wished to recommence competitive rock climbing within 8 weeks. The referring doctor requested an immobolisation device be worn for 14 days.

Due to the unusual nature of this injury, our clinic had no pre-fabricated A2 rings in stock. In order to immobolise the finger as soon as possible, a custom-made device was prescribed. The aim of the device was to immobolise the finger between the MCPJ and PIPJ and low temperature thermoplastic was used.

The custom made hand spica fits the orthotic prescription but allows some slight movement of the ring finger in the device. This was due to the trimlines being too low anteriorly and also because the Velcro strap, although adjustable, doesn’t provide complete surface coverage. The patient reported issues with the strap chafing, hence why it was made smaller and taken further away from the finger webbing. This device was modelled on the more common boxer’s splint but incorporated elements of a number of different hand orthoses. If this device was to be made again, a better option may be to incorporate the 3rd digit instead of the 5th but this may be too restricting to overall hand movement. Another alternative may be to apply the thermoplastic with the fingers in full extension at the MCPJ rather than slight flexion. However, again the slight flexion allowed a more functional hand position and this would be sacrificed if full extension was enforced.

The patient states that this device is comfortable and practical. In order to solve the issue of the slight immobolisation, the patient and I agreed that they would buddy tape their fingers over the device, as it is only to be worn for two weeks. The device provides a rigid material for the buddy tape to be applied over, allowing complete immobolisation. The device also provides a reminder to the patient that they need to mindful of using their fingers.

A few outcome measures were tested with this patient. A DASH score of 23 was found whilst the patient was wearing the device. This isn’t a great measure of the capabilities of the device as it is designed to immobolise the fingers. Manual muscle testing of the finger flexor once the device has been removed may be a good indication of the recovery of the flexor pulley. The best outcome measure, however, will be the patient’s own observation of strength once they return to climbing in 6 weeks’ time.

Outcome measures
A number of outcome measures were tested with this patient. They included a DASH assessment, an Upper Extremity Functional Index, ROM testing and Muscle Grading.

ROM testing- The ROM of two joints of the injured finger were tested. These were the CMC and PIP joints. Both of these joints showed a full range of flexion and extension but caused some pain, meaning that the injury has only altered the strength of the muscles, not the ROM.

Muscle Grading- The finger flexor muscle was graded on a scale of 0-5 and received a score of 4, where it could be moved against gravity and some resistance. However, the more resistance was applied the greater the pain level.

DASH (Hudak, Amadio, & Bombardier, 1996)- The patient scored 23 on this assessment. The DASH is interpreted by considering the score as a number out of 100, where higher numbers equal greater disability. A score of 23, therefore, indicated only mild interference in daily life, which is consistent with the patient’s subjective opinion about the injury.

The Upper Extremity Functional Index (Stratford, 2001)- asks a number of questions related to daily activities, and is very similar to the DASH test. Performing both of these is probably unnecessary, but for the sake of being thorough the patient was asked to complete both. The patient scored 60/80 on the UEFI. In the opposite way to the DASH, lower scores on the UEFI indicate more severe disability. This outcome measure also suggests, like the DASH, that this patient is not significantly disabled by this injury.

There are a number of basic outcome measures that can be performed with patients but in the case of this patient, they don’t really tell us a whole lot. This patient’s main deficit is sport-related, so apart from a small section of the DASH that considers the impact on sport, this is not really addressed in these outcome measures. Because the patient scored quite well on both the DASH and UEFI there is not a lot of improvement to be made. This doesn’t mean the injury isn’t significant in some aspect of the patient’s life, in this case sport and recreational activities.

These outcome measures weren’t really helpful in determining the improvement for this patient. All tests would be performed in 6 weeks’ time after the patient has completed their physiotherapy rehabilitation, and the scores would be expected to be normal. If they weren’t, then this may indicate a persistent strength deficit of the finger flexor and surgery may need to be considered. The best measurement of success for this patient, however, is going to be the patient’s own subjective opinion of the strength of their finger when they begin rock climbing again.

Referral Letter
To John Young, I am referring to you a 28 y.o female patient who presented to our clinic 1/52 after injuring her finger whilst rock climbing. The patient is an experienced and competitive rock climber. The patient was assessed at Barnes St Health Clinic by Dr. Herbert Spence, who referred the patient to our clinic for further assessment. Dr. Spence diagnosed a rupture of the Finger Flexor Annular Pulley A2 on the client’s right hand ring finger. The Dr. requested an immobilisation device be worn for 14 days.

On presentation to our clinic, the patient’s finger was observed. It was swollen and hot, but had no evidence of bowstringing. The patient was experiencing only minimal pain that increased during a grip test. The patient had full ROM at the CMC and PIP joints and had a finger flexor muscle grade of 5.

As this is an unusual injury, no pre-fabricated immobilisation devices were readily available at our clinic. As such, I custom-designed and moulded a Low Temperature Thermoplastic hand orthosis. The device encompasses the ring finger and the 5th digit, but did not adequately immobilise the ring finger over the PIP joint. The patient has been buddy taping their fingers over the top of the thermoplastic device to add extra support.

This patient’s goal is to return to competitive rock climbing in 8/52. The immobilisation device has been worn for 5 days at the time of referral. It needs to stay on for another 9 days, at which time I would like the patient to visit you. The patient will need to slowly begin using their finger again, but as the injury is still healing this will need to be done in stages, so as not to re injure the finger. In order to regain full strength, I believe it is in the patient’s best interest to work with you to incorporate exercises and tasks that mimic the rock climbing environment. I trust that you know the best rehabilitation methods. If this patient notices a persistent strength deficit in their finger, might I suggest you refer back to Dr. Spence as surgery may be necessary.

If you have any questions or queries regarding this patient or the current orthotic management, please don’t hesitate to contact me.