4 May 2010

A2 pulley injuries review re-posted

Disruption of finger flexor pulleys in rock climbers: prevalence, diagnosis and strategies for rehabilitation.
NB: This article was formerly in the articles section of my old website. It was really popular so I’ve reposted it here.
Background
The sport of rock climbing has developed into a mainstream, competitive sport with considerable popularity. This growth is likely to be partly attributable to the virtual elimination of the significant danger aspect in rock climbing, within the disciplines of sport climbing (routes protected by pre-placed anchor bolts) and indoor climbing. In addition, the explosion in numbers of indoor climbing centres and organised competitions in most cities in Europe and the U.S. have prompted a significant rise in participation. The focus of these new disciplines is the gymnastic, athletic and competitive aspects of movement on rock (Jones 1991).
The history of structured and specific training patterns in rock climbing spans only the past few decades (Morstad 2000). Today, considerable sport specific literature together with increased availability of climbing facilities has fuelled a dramatic rise in standards throughout the sport, such that its basic biomechanical demands have changed and continue to change. Today’s hardest rock climbs feature angles up to and beyond 45 degrees beyond vertical (Goddard & Neumann 1993). On such overhanging terrain, the legs cannot support much of the body mass in the vertical direction; they can only push the body along the plane of the surface (Fig 1). As the angle increases, the forces exerted shift increasingly to the smaller muscles of the upper limbs. This area is also the focus of rock climber’s training regimes with exercises such as ‘deadhanging’ (isometric hangs from fingertip edges) and ‘campus boarding’ (a form of training based on plyometrics which involves jumping between fingertip sized rungs on a wall) (Goddard & Neumann 1993; Morstad 2000). The forearm, specifically the finger flexors have been identified by several studies as the most significant centre of muscular fatigue during rock climbing (Watts 1998). 
Figure 1. Elite level climbing places high demands on the fingers.
In climbing movements, the fingers produce tension on a hold to support a proportion of the body mass while the elbow and shoulder joints flex to pull the body upward. The isometric contraction of the finger flexors is interrupted when reaching towards the next hold. Finger flexor strength has been shown to be a determinant of performance in rock climbing (Bollen & Cutts 1993; Grant et al 1996). 
Holds used by climbers, even at a recreational level are remarkably small (often less than 10mm deep) and can often accommodate only 1-4 digits (Bollen 1990). Several different grip styles can be used to maximise the force produced on holds (Goddard & Neumann 1993). Bollen identified one style in particular, known as “crimping” which is of particular relevance to injury patterns among climbers. It is thought that over 90% of climbers use this grip style regularly (Bollen 1988). Crimping involves placing the fingertips on the hold with the distal interphalangeal joint (DIP) held extended while the proximal interphalangeal joint (PIP) and the metacarpophalangeal joint are held flexed. 
An early study investigating common rock climbing injuries reported that the hand and wrist was the commonest site of climbing related injury (Bollen 1988). Incidence of pain, sometimes accompanied by swelling on the volar aspect of rock climber’s fingers, often centred near the PIP joint was a common complaint (Bannister & Foster 1986; Bollen 1998). Bollen hypothesized that the site of such injury might be the flexor pulley system. The purpose of the flexor pulleys is to maintain the position of the flexor tendons, flexor digitorum superficialis (FDS) and flexor digitorum profundis (FDP) close to the phalanges. In a 1988 case study Bollen observed pain and swelling over the volar aspect of the proximal phalanx of the middle finger in a 20 year old rock climber. Avulsion of the FDS of FDP tendons was ruled out, as flexion against resistance was possible. There was visible and palpable ‘bowstringing’ (bulging of the flexor tendons away from the phalanges) at the PIP joint, pointing to rupture of one or more of the flexor pulleys. There is no mention of any confirmation by imaging of this diagnosis. The climber described the injury as occurring suddenly while holding onto a ‘pocket’ hold with only the middle and ring fingers. The climber’s feet slipped and caused sudden increased strain on the fingers, with immediate pain, swelling and subsequent bruising experienced locally on the affected finger. Bollen suggested that this type of injury was already well known among climbers and the study prompted a larger investigation of its prevalence. Pulley injuries among climbers had already been described in the French and German literature (rock climbing is particularly popular in both countries) as early as 1985 (Schweizer 2000).
Prevalence
Bollen & Gunson (1990) examined 67 world-class climbers at the first ever rock climbing indoor world cup event in 1989 for signs of current of previous hand injury. Flexor pulley injuries constituted by far the most common complaint, affecting 26% of the climbers, mainly affecting the ring finger. The injury was diagnosed by observation and palpation of flexor tendon bowstringing on resisted flexion compared to the same finger on the other hand. The injuries had occurred suddenly while falling or slipping while pulling maximally on a small hold, causing localised pain and varying degrees of swelling and bruising on the affected finger. Again, no imaging was used no attempts were made to classify the severity of the pulley injury. It was noted that the climbers considered firm taping with non-stretch zinc oxide tape around the affected part of the finger allowed continued training in the presence of injury and made the injury “feel better”. 
A more recent study (Wyatt et al 1996) reported one case of pulley injury in nineteen climbers presenting to a local A & E with a range of climbing related injuries. A comprehensive review of patterns of all types of rock climbing injury by Rooks (1997) suggested that 30% of all injuries are centred around the PIP joint and that such injuries are present in 50% of sport climbers. The study suggests possible PIP injuries comprise of flexor pulley tears, FDS insertion rupture or PIP collateral ligament strains. Rooks suggests that any of these injuries may progress to fixed flexion deformity or contracture of the PIP joint and athroses. Bollen & Gunson (1990) also found evidence of fixed flexion deformity in 24% of climbers as well as chronic PIP collateral ligament injury and two cases of FDS tenoperiositis. 
Rohrbough et al (2000) studied the prevalence of ‘overuse’ injuries in a group of elite climbers attending a national level climbing competition (n = 42). Collateral ligament injury at the PIP joint was most prevalent (40%) and only 1 competitor had no signs of upper extremity injury. Evidence of A2 pulley injury was present in 50% of the climbers. 26% of these showed evidence of bowstringing while a further 24% had pain over the A2 pulley but no clinical bowstringing. The authors suggest that A2 pulley injury where bowstringing is absent is the result of an isolated pulley rupture. Other finger injuries described included flexor tendon strains (referred to as Flexor unit strains) and tendon nodules. The authors note that most subjects who had consulted health professionals following their injuries reported a lack of appreciation by professionals for the demands of climbing on the body, and little help with diagnosis or treatment prescription. Gabl et al (1999) suggested that prevalence of flexor pulley injuries among recreational climbers (outside the professional competition circuit) might be far greater than the literature would suggest. Most case studies have been based on patients who present to medical practitioners with an injury. Gabl suggests that 60-70% of injured climbers do not seek medical attention. Both Gabl et al (1998) and Bollen & Gunson  (1990) sampled elite competitors at an international event. Clearly, this sample excludes those competitors who are in layoff due to injury.
The general finding from the studies described above is that PIP joint injuries among rock climbers are most prevalent on the middle and ring fingers. It is likely that this is because these fingers are most often used on ‘pocket’ holds, which can only accommodate two fingers. Other pathologies in this area, which have been described, include tenosynovitis (Bannister & Foster 1986) and abnormalities of the phalanges (Bollen & Wright 1994). The radiographic changes included formation of thickenings of the proximal phalangeal cortices at the attachment of the distal edge of the A2 flexor pulley.
Given the range of injuries experienced by rock climbers centring around the fingers and the PIP joint in particular, there is a clear need for application of detailed knowledge of the functional anatomy of the fingers in diagnosis of finger injuries. Furthermore, there needs to be an establishment of sound and thorough diagnostic techniques for climbing related injuries to ensure appropriate treatment is subsequently applied.
Functional anatomy of the flexor pulley system
The flexor tendon sheath of the fingers is a continuous connective tissue structure running from the metacarpophalangeal joint to the DIP joint. The transverse fibres of the palmar aponeurosis may also be considered part of the pulley system (Phillips et al 1996). The flexor pulley system is a series of thickened fibrous tunnels running across the flexor tendons that maintain and stabilise the position of the flexor tendons close to the phalanges during flexion (Martinoli et al 2000). There are five annular pulleys, A1-A5, positioned where the sheath is required to be stiff. Three cruciate pulleys, C1-C3, are aligned over the tendons where the sheath must flex. The continuous flexor sheath contains a synovial membrane that allows tendon gliding and assists (along with the vinculae tendinum) with tendon nutrition.
The A1 pulley is situated anteriorly to the metacarpophalangeal joint capsule. The A2 pulley lies over the proximal phalanx. This pulley is the longest pulley and has a well-developed distal free edge containing synovial fluid. A2 is considered the most important pulley as flexor pulley system function is most affected by excision of this pulley. There are well-defined ridges on the proximal phalanx where the A2 pulley attaches, particularly at the distal edge. These attachments can become thickened in climbers as age advances (Bollen & Wright 1994). A1 and A2 must absorb bowstringing forces from both the FDS and FDP flexor tendons. The A3 is a narrow pulley overlying the PIP joint capsule. The A4 pulley, again slightly longer than the joint pulleys, lies over the centre of the middle phalanx. The smaller and only recently described A5 pulley lies over the DIP joint (Phillips et al 1996). During flexion, the cruciate fibres become more transversely aligned and the edges of the annular pulleys draw together to become a continuous fibrous tunnel. The length of each pulley varies with the length of the digit and thickness varies with the relative length of the pulley.
The mechanical advantage or moment arm of the flexor tendons depends on the perpendicular distance between the joint and tendon. The flexor pulley system effectively reduces the moment arm of the tendons over the finger joints by keeping them very closely apposed to the phalanges. By doing this, the tendon excursion required to provide a given range of joint flexion is greatly reduced. The pulley system permits 180 degrees of angular motion across the PIP and DIP joints for 2.5 cm of tendon excursion (Rispler et al 1996). This function is important and makes physiological sense as muscles are capable of producing extremely large forces but incapable of shortening many times their own length (Hunter et al 1984). Thus, an intact pulley system is considered essential for normal hand function and pulley ruptures are regularly treated by surgical reconstruction (Lin et al 1990). Sectioning of the A2 and A4 pulleys results in a need for 30% greater tendon excursion to obtain an equivalent PIP joint flexion (Le Viet et al 1996).
In addition to its importance in maintenance of appropriate lever arms, an intact pulley system, through its effects on tendon excursion, is essential for flexor tendon function and health. The flexor tendons of the hand do not ‘glide’ as such through the synovial and fibro-osseous sheath. The tendons are attached to the paratenon that surrounds it (Hunter et al 1984). This relatively elastic tissue is relaxed during the mid-point of tendon motion. When the fingers are more flexed or extended, thus the peritendinous structures are stretched. This stretching uses energy and has been recognised as an important factor in tendon transfer. Furthermore, abnormal patterns of tendon excursion (the result of pulley malfunction) cause the phenomenon of ‘creep’, where the surrounding structures become permanently stretched. This effect causes an inflammatory reaction that eventually results in additional fibrous tissue deposits. It has also been shown that fibrous tissue deposits form under the bowstringing flexor tendons in the presence of pulley tears. Both these phenomena lead to flexion contracture, a condition that has been described in rock climbers suffering from pulley injury.
Strength and efficiency of the flexor pulley system
The pulley system of the middle finger is the strongest of the digits, followed by the index, ring and little fingers (Bowers et al 1994; Marco et al 1998). The strengths of the individual pulleys have been extensively studied with varying results (depending on testing protocol), as have the effects of pulley excision. 
Pulley excision or rupture causes varying degrees of loss of flexion, depending on the extent and position of the pulley rupture. Tropet et al (1990) noted that in a rock climber diagnosed with A2 pulley rupture, active flexion of the PIP joint was impossible. Yet when the affected finger was gripped anteroposteriorly by the examiner, flexion became possible once more. Lin et al (1990) studied the mechanical properties of the pulleys in cadaveric specimens. They found that the maximum breaking strength (Newtons/mm pulley length) were similar for the annular pulleys. However, due to the different lengths of the pulleys, the maximum breaking loads differed significantly. A2 was strongest (407 N) followed by A1 and A4 (209 N). A3, A5 and the cruciate pulleys had much lower breaking loads (<100 N). Load deformation curves were also produced, showing that A2 and A4 tend to be stiffer and less deformable than the other pulleys. An important conclusion from this study was that surgical reconstruction of pulleys should pay attention to pulley position, thickness and length. When pulleys were reconstructed using a ‘belt loop’ technique, near normal breaking strengths could be achieved. Bollen (1990) suggested that the force produced on the pulleys by a 70 Kg man supporting his body mass through one finger using a ‘crimp’ grip would be sufficient to exceed the breaking strengths reported by Lin et al. A similar study (Marco et al 1998) suggested that such an estimate may be an underestimation and the forces produced by supporting body weight may be three times as great as the breaking strengths recorded for pulleys in their cadaveric specimens. However, it is recognised by Marco et al that he age and fragility of the specimens may have adversely affected pulley strength. 
Marco et al replicated a ‘crimp’ grip and measured breaking strengths of the pulleys with the hand and flexor system essentially intact. The flexor tendons were attached to a loading device and force was applied until failure of all the pulleys and ultimately avulsion of the flexor tendons. With this grip, a distinctive pattern of failure was observed in most cases. A4 ruptured first, followed by A3, A2 and finally the FDS and FDP tendons. A1 did not rupture in any of the 21 fingers tested. Breaking loads were significantly lower that of Lin et al. Lin et al used specifically designed hooks to load the pulleys evenly. In vivo, the forces on the pulleys during ‘crimping’ may be unevenly distributed, creating a ‘cheesewire’ tearing effect. Marco et al suggest that the absence of skin on the volar aspect of the specimens may have reduced the breaking loads observed. These authors also observed that once pulleys A2-A4 had ruptured, the direct transfer of bowstringing force of the FDP tendon of the overlying FDS tendon caused avulsion of FDS. This finding has clinical significance, demonstrating the need for prudent management of pulley injuries in order to prevent the more serious complication of tendon avulsion.
Bowers et al suggested that occurrence pulley rupture in vivo is dependent on the degree of flexion of the finger. They suggest that the correct conditions for pulley injury are created when a sudden additional force is applied while the pulleys are already loaded and the finger is flexed to a high degree. In their case study of nine patients with pulley rupture, the A2 pulley ruptured first. Again A1 ruptures were not observed. Several other case studies have suggested that A2 pulley rupture is the most common injury among climbers (Cartier et al 1985; Tropet et al 1990; Moutet et al 1993; Gabl et al 1998). Many of these studies used evidence of clinical bowstringing across the PIP joint as the main diagnostic indicator of A2 injury. However, Marco et al observed that pulley ruptures rarely occurred as isolated events and that clinical bowstringing was only evident after A2-A4 had ruptured, a finding supported by 16 case studies by Martinoli et al (2000). Le Viet et al (1996) observed both isolated A2 and A4 ruptures as well as combined injury to the pulleys in seven patients.
Rispler et al (1996) identified a need to detail the efficiency of each flexor pulley in order to determine the functional importance of each. The rationale for this is that during reconstructive flexor tendon surgery, the surgeon must balance a need to preserve pulley function for reasons outlined above and allow sufficient access to the flexor tendons to allow repair and prevent postoperative adhesions forming. Rispler and co workers examined the effects of random pulley excision on a range of functional measures, using cadaver specimens. A5 sectioning produced no difference in tendon excursion efficiency or work (force produced by the flexed finger multiplied by excursion) efficiency, and was deemed expendable. Similarly, A1 sectioning had no impact on excursion and actually improved work efficiency of the flexor system. A2, A3 and A4 each made significant individual contributions to tendon function. However, A2 sectioning alone produced little reduction in work efficiency despite significantly affecting excursion. The authors concluded that A4 rather than A2 was the most important pulley, contradicting earlier findings. The authors recommend that reconstructive surgery should aim to preserve at least A2-A4 in order to protect normal functioning.
Diagnosis of pulley injury
The importance of accurate diagnosis for preventing further injury and preserving normal hand function has been clearly outlined above. Greater understanding among physicians of the nature and demands of rock climbing would benefit appreciation of the mechanism for pulley injuries. However, such injuries have also been documented in non climbers (Le Viet et al 1996). There are several methods of assessment of suspected pulley injuries available. In addition, there are some prevalence issues that are of note here.
Early studies used the appearance of clinical bowstringing as the main indicator of pulley tears. The appearance of bowstringing is clearly a simple and conclusive method of diagnosis at the initial examination of the patient. Depending on the extent of the injury (i.e. how many pulleys have ruptured), bowstringing may be apparent on the volar aspect of the proximal phalanx, PIP joint, distal phalanx or all three. Bowstringing maybe visible and palpable in the resting finger, but due to the weak pulley effect of the skin, palpation during resisted flexion should also be performed. Active flexion should be possible by the patient in the absence of tendinopathies, but range may be severely limited if several pulleys are damaged. In addition, late presentation by the patient may result in the development of fixed flexion contracture by mechanisms discussed above. Several studies have indicated that isolated pulley rupture may not produce sufficient bowstringing to be detectable either at examination or by a range of imaging techniques (see below). Thus, more information should be sought at examination. 
If the injury is fresh, there may be evidence of local swelling, tenderness and pain over the affected area. The patient should be questioned about this and the occurrence of the injury. Pulley ruptures commonly occur during ‘crimping’ manoeuvres during climbing, especially if there was a sudden additional loading due to a hand or foot slipping off a hold. Injuries are more common while climbing in cold weather of while warming up. Patients have also commonly experienced an audible ‘pop’ or ‘bang’ at the time of rupture, sometimes accompanied by pain and immediate swelling. However, these indicators do not necessarily occur in limited or partial pulley tears (Rohrbough et al 2000). 
Imaging has been used to detect clinical bowstringing and reinforce the findings of initial examination. Imaging is often expensive and may only be necessary when the findings of an examination are unclear. This may often be the case if pain and swelling interfere with the examination procedure. The merits of using various imaging modalities have been reviewed in the literature. MRI, CT and ultrasonography have all been used successfully to detect bowstringing. X-ray scanning is not helpful to pulley injury diagnoses unless injury to bony tissue is suspected (Bowers et al 1994). For example, x-ray may be required if avulsion of one of the flexor tendons at its insertion is suspected. Le Viet et al (1996) reported excellent results in visualising flexor tendon bowstringing using computed tomography (CT) scanning on a sagittal plane. Bowstringing was more obvious when the finger was scanned while flexed against resistance. The authors recommended this type of imaging as comparative examination of the opposite finger and use of flexion against resistance is possible. 
Gabl et al (1998) used MRI scanning on sagittal and coronal planes both to confirm diagnoses and measure a range of clinically relevant variables. The researchers were able to diagnose both complete isolated tears and partial pulley tears (of A2) using MRI. Such detailed information on the extent of the pulley damage was possible as the extent and position of the flexor tendon bowstringing was clearly visible. Patients with incomplete pulley tears were successfully treated with a non-operative treatment protocol. The main finding of the study was that bowstringing, observed at MRI that extends proximally as far as the base of the proximal phalanx should be treated with surgical reconstruction.
Given the expense and limited availability of MRI and CT scanning, more recent research has examined the effectiveness of ultrasound as a viable diagnostic tool for pulley injury. Klasuer et al (1999) recognised the potential of ultrasonography in this area as it can detect soft tissue anatomy and inflammatory changes. It was hypothesised that this type of imaging may be of particular use for finger injuries as the required penetration depth is low, allowing increased resolution with use of higher scanning frequencies. This study provided valuable information on the anatomy and pathophysiology of the pulley system. By comparing a group of 34 elite climbers who had recently experienced suspected pulley injury to age and sex matched controls several variables could be measured to establish patterns in health and disease. It was demonstrated that clinical bowstringing was completely absent even during resisted flexion in controls. This demonstrates the relative inelasticity of the pulley structures. 26 symptomatic fingers among the climbers demonstrated increased (0.14 cm) flexor tendon to phalanx distance. A further 3 demonstrated bowstringing of 0.31 cm with complete rupture of the A2 pulley confirmed by subsequent MRI scanning. This result points to a greater proportion of partial tears among climbers than previously recognised in the literature. The climbers also demonstrated increased flexor tendon thickness (0.56 cm) compared to controls (0.42 cm). In addition thickening of the A2 pulley was observed in the climbers (0.11cm) compared to controls (0.08 cm). Several other pathologies were observed on the climbers including tenosynovitis, cysts, and thickening of the PIP joint capsule. In addition tendon gliding function could be visualised in real time. Thus, Ultrasound is a highly attractive modality for the imaging of this type of injury. However, other studies have raised concern about the requirement for considerable skill in interpretation by the radiographer and the potential inter-observer variability. 
Another study (Martinoli et al 2000) compared the effectiveness of ultrasonography and MRI scanning in 16 injured elite rock climbers. Again, healthy fingers showed the flexor tendons aligned very close to the phalanges at ultrasound scanning. The pulleys were again visible as a hyperechoic line on the volar aspect of the tendons. Again, partial tearing of the A2 pulley was diagnosed by thickening of A2 in the absence of significant bowstringing. The diagnoses from MRI and ultrasound scanning correlated well. Ultrasound was recommended by the authors as a viable and inexpensive method of scanning finger injuries to achieve accurate diagnosis. 
Non-operative treatment protocols
There are two main protocols available to treat pulley tears, pulley reconstruction at surgery or conservative treatment with rest, splinting and NSAIDS. The factors influencing the decision of the practitioner as to which protocol to choose includes how old the injury is, success of previous conservative treatment, competitive level of the athlete being treated, the age of the patient and most importantly, the extent of the pulley damage. 
As discussed above, the prevalence of isolated partial tears among climbers may have been underestimated by the literature. Patients with partial tears, often of A2 are not thought to be at risk of fixed flexion contracture or flexor tendon avulsion (providing appropriate treatment and advice are given) and may even have been able to continue training with the injury (Bollen 1988). Thus, non-operative treatment is recommended in these cases (Gabl et al 1998). Some of the studies discussed above have used splinting of the injured finger followed by gradual progressive increases in use before resumption of previous levels of training. All studies have reported successful results and it is thought that the flexor pulley system repairs well compared to other connective tissue structures. However, Rohrbough et al (2000) indicates that there remains some disagreement between researchers as to the treatment of pulley tears. Tropet et al (1990) suggested that conservative repair may lead to a chronic weakness of flexion. However, there are numerous reports of successful return to top level climbing following pulley tears (Bollen 1990) and chronic bowstringing should theoretically translate to increased strength in the finger flexors by increasing mechanical advantage (at the expense of range of motion). The main components of non-operative treatment regimes are discussed below. 
If the injury is fresh, then a standard RICE procedure should be followed. However, many cases present several weeks or even months after the initial injury as normal daily life activities are not adversely affected by partial tears. There is little information available in the literature regarding splinting techniques. Techniques used for post-operative treatment are discussed below. Some literature has suggested layoff from climbing for up to 3 months. However it is well known that underuse results in sometimes severe degeneration of connective tissue structures as well as muscles (Kirkendall et al 1997). Hunter et al (1984) suggests that passive range of motion and gentle activity should be commenced after three weeks. Sandmeier & Renstrom (1997) conclude from a review of treatment principles in tendon disorders that exercise should be encouraged and will promote healing. It is added that resumption at a lower level of the athletes sport may cause frustration and over ambitious rates of progression, leading to re-injury. Thus, an alternative therapy such a squeezing a ball may be useful. However, while such therapy is useful in promoting healing in the injury, it does not prevent atrophy of other healthy tissues. These concerns are of particular relevance in rock climbing as very few athletes, even at world class levels have a coach to monitor and discipline the rehabilitation program. 
Given the fact that several different grips can be used in rock climbing, it should theoretically be possible to resume climbing as soon as the inflammatory phase is over. If the climber uses only an open handed grip (Goddard & Neumann 1993) where the DIP joint is flexed and the PIP joint remains at zero degrees of flexion. Using this grip, only the A5 pulley is required to resist a flexor tendon bowstringing effect, and injury to this has not been described in the literature. In the presence of pulley tears, bowstringing does not occur unless the PIP joint is flexed. Moreover, patients with pulley tears report that pain from the injury disappears when this grip is used for climbing (Schweizer 2000). However, such a protocol may be difficult and dangerous for the climber to undertake as the crimp grip is widely used and is likely to be habitual. It is plausible that finger exercises performed on a finger board with strict adherence to an open handed grip (routinely used in normal training patterns) may be a safer method of preventing atrophy of other tissues during rehabilitation and promoting psychological health of the injured athlete. There are no reports in the literature of the viability of this technique.
NSAIDS may be of use to control excessive inflammation where an injury becomes chronic. Indomethecin has been shown to increase tendon strength and collagen content (Kirkendall et al 1997). The rationale for using NSAIDS during rehabilitation of connective tissue areas is primarily to reduce inflammation, which is assumed will lead to a speeding up the healing process. A secondary objective is to reduce pain from the injury, either in the acute phase or later, to allow a resumption of the activity. Reviews of the use of NSAIDS in healing have reported unconvincing results (Sandmeier & Renstrom 1997). It is clear that the inflammatory phase is a vital stage in healing and mediates initiation of the later stages of repair. Gailey & Raya (2001) suggest that therapeutic interventions should not necessarily be aimed at eliminating inflammation, but rather “maximizing the conditions for connective tissue regeneration”.
Chronic inflammation and edema at the site of an injury may result in certain phagocyte cells with short lifespans to die and leak their enzyme contents into the injury site, thus damaging healthy tissue. In addition the high pressures caused by excessive edema reduce blood flow to the area. The enzymatic reactions involved in collagen synthesis are dependent on oxygen availability at the injury site (Anderson et al 2000). Under normal circumstances, the inflammatory stage of repair lasts only a week or so. After this period is completed, rehabilitation should focus on increasing blood flow to the injury and improving range of movement.
Stretching is recognised as an important promoter of formation of strong compacted scar tissue (Gailey & Raya 2001). Two types of finger flexor stretch have been detailed in climbing literature. These involve pulling the finger in the varus direction, effectively hyper extending the metacarpophlangeal joint and PIP joint (Gresham 1996). Deep friction massage (DFM) has been successfully used to treat ligament tears and promotes local hyperaemia, analgesia and reduction of adhesion formation. DFM is applied perpendicular to the direction of the fibres in the tissue being treated. The aim of this therapeutic modality is to separate fibres, mechanically assisting alignment in the appropriate direction. Flexor pulley fibres run in a transverse direction and it follows that massage should be longitudinal along the affected finger. Studies have shown that the effects of DFM are dependent on mechanical force. Heavy pressure must be applied to promote fibroblast proliferation.
A relatively poorly understood method of increasing local blood flow is ice massage. Ice is routinely used to reduce circulation, swelling and pain during the acute inflammatory phase. In this type of therapy (cryotherapy) significant cooling is applied to reduce the skin temperature to 12-15 Celsius. This results in vasoconstriction and resultant reduced blood flow. However, it has been observed that more gentle cold application to a small area around the injury has a somewhat different effect. The skin temperature should not fall below 15 Celsius. After a brief period of vasoconstriction, there is a large reactive hyperaemia. Lewis first described this reaction in the hands in 1930. The Lewis reaction is thought to be a tissue protective mechanism, but its function is not well understood (Lemons & Downey 2001). The reactive vasodilatation occurs after 30-40 minutes of cold application and when the hand is sufficiently warm once more, vasoconstriction occurs once more and the pattern continues in an oscillating fashion. Thus, the treatment should ideally last 30-40 minutes and should involve only moderate cooling. 
Circumferential taping of the injured pulley is widely and routinely used for both prevention and rehabilitation of pulley tears among rock climbers. Non stretch, zinc oxide tape of 1.3 cm width is used. Schweizer (2000) tested the effectiveness of pulley taping. The findings were that taping was minimally effective in relieving load from the A2 pulley. The effect was maximised (10% of bowstringing force) when the tape is positioned near the distal end of the proximal phalanx. The tape absorbed progressively less bowstringing force as the force produced at the fingertip increased. This result has two implications. Firstly, taping is likely to be most effective during the earlier stages of rehabilitation when the forces produced by the fingers are lower. Secondly, taping is unlikely to prevent pulley injuries, as these are likely to occur when forces on the pulley are maximal. This finding is supported by Warme & Brooks (2000) who showed that taping had no effect in preventing pulley ruptures in cadaveric specimens.
Surgical pulley reconstruction
There is disagreement in the literature about the requirement for surgical repair of pulleys. While it is clear that an intact pulley system is crucial to long term hand function, successful repair can occur with conservative treatment. Surgery if often carried out where there is complete rupture of more than one pulley. Various techniques have been used to repair pulleys. Where the ends of the pulley are intact, a simple end to end suture or Kapandji’s technique (Tropet et al 1990) has proven effective. Otherwise grafting from the FDS tendon or palmaris longus is generally performed (Hunter et al 1984). Repair of at least A2-A4 is necessary to retain normal function and prevent fixed flexion contracture. Ideally all pulleys should be repaired and A2 should be greater than 0.5 cm wide in order to adequately withstand bowstringing forces (Lin et al 1990). Studies have shown that correctly repaired pulleys can reach similar breaking loads to healthy pulleys. Patients are kept in a dorsal extension block plaster split for three weeks with the interphalangeal joints in extension. Passive motion exercises are commenced immediately after. 
Prevention
As discussed above, circumferential taping is of limited preventative value. Decreased reliance on the crimp grip, cautious use of holds which fit less than three digits, and a more controlled climbing style have all been recommended to avoid injury. (Goddard 1993). Attention should be paid to the feet as well as the hands as pulley tears often occur as a result of additional loading following the slip of a foot. Gradual progression in training load and thorough warm up and stretching procedures are also important (Gresham 1996). Warm up has been shown to improve the elastic properties of the flexor pulleys (Schweizer 2000). Diet is another factor influencing tissue health and thus predisposition to injury. O’Brien (1997) suggests that adequate supply of proteins, carbohydrate, vitamins and various minerals, particularly iron, manganese, copper and zinc are important for connective tissue turnover. 
Summary
The crimp grip used by 90% of rock climbers produces extremely high bowstringing forces from the finger flexor tendons on the digital annular pulley system. Partial tears of isolated pulleys or more significant rupture of several pulleys at once are the most prevalent injury among climbers. Injury is most often found in the A2-A4 pulleys and these pulleys are essential for normal hand function. Bowstringing may be palpable at examination, allowing diagnosis of pulley injury. Various types of imaging will assist accurate diagnosis, especially if examination is not possible. If several pulleys are ruptured, surgical reconstruction is recommended. In less serious tears, non operative rehabilitation has been shown to be successful in restoring normal function and previous levels of sport performance. Rehabilitation should include several techniques for increasing blood flow to this relatively avascular tissue. Taping of the flexor pulleys is of benefit during the early stages of repair but is unlikely to prevent pulley injury.
References
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2 comments:

Harry said...

Hi Dave,

First and foremost, I would like to thank you for the wealth of knowledge your blog has provided me on pulley injuries in general. I damaged my A2 pulley approximately two and a half months ago and am climbing relatively strong again.

My question is partly in reference to a post you made regarding pulley/tendon recovery and mentioned using a combination of hot and cold water baths to increase blood flow. I am finishing up my engineering degree here in Canada and have taken on the topic of increasing digital blood flow as a final report for my bio fluids class. Do you know of any journal articles that reference this material or have some other techniques you would be willing to share?

Thanks for your time,
Harry

Nick Youds said...

Hi Dave,

I was wondering how much research if any has been done on the function of the palmaris longus muscle for non-normal activities. From what I've read it's vestigial, because it was useful for climbing during a time when having one would provide some sort of adaptive fitness advantage (perhaps escape) to the possessor when such things were "normal" activity.

I'm really curious to learn more about the PLM (w/ citations to the relevant PR literature), what sort of advantages to gives to climbers (if any), and if a graft from the plantaris muscle would be more appropriate for those who are climbers.

I fear that whether or not it turns out to have a function in climbing, it has not been thoroughly examined enough to make such a statement especially considering that climbing ability was probably not a criteria used to determine whether is was useful or necessary to prolong "normal" hand activity.

Again, I'm not concerned with whether someone can climb without it (Tommy Caldwell after all seems to perform very well with what most would consider to be a more serious disadvantage), but if having one versus not having one translate into improved climbing ability no matter how slight.

Thanks for your time and insight!
Nick Youds