Principles in the management of a mangled hand.

Mangling hand injuries are high energy complex conditions that are challenging to manage. They require careful planning and meticulous execution of treatment. A clear set of anatomical and functional goals at the outset guides the planning. The first surgery is crucial to ensure good vascularity to the salvaged tissue, prevent infection and achieve bony stabilization. Re-look surgery and definitive reconstruction can then follow. Post-operative therapy is an important component of treatment. Despite best efforts, outcomes are variable in these devastating injuries. Secondary procedures and provision of prostheses will do much to improve the patient's body image and limb function. This article provides a set of principles that will guide the assessment and treatment of such injuries.

INTRODUCTION

The hand is always exposed to environment during use and easily at risk of injury. These injuries occur in the setting of work, home accidents, assault, and motor vehicular type accidents. Mangling or mutilating hand injuries are commonly encountered in different societies as mechanization provides risks for these types of injuries. These injuries occur as a result of high-energy trauma in a young and otherwise healthy patient population.[1]

The mangling hand injury provides one of the greatest challenges to the hand surgeon. The variability of the tissues injured and lost, and the requirement for complex reconstruction to restore and salvage hand function, requires careful planning and meticulous execution of treatment. The ultimate aim is to restore sufficient function, so that the patient can perform their activities of daily living, and return to work.[2]

This article will provide the principles necessary for management of these injuries.

WHAT IS A MANGLING HAND INJURY?

The definition of mangling or mutilating hand injury is imprecise. The origins of the term provide a useful start point. “Mangled” has its origins from old French meaning “cut to pieces,” and mutilating from Latin meaning “to cut or lop off,” and mutilus “maimed”.[3] Together, the terms indicate an injury with significant loss of tissue and loss of function.

From the opposite viewpoint, the minimal components required for reasonable hand function provides a reference point beyond which a hand injury might be considered mutilating. Pinal addressed the issue of what makes an “acceptable hand”.[4] He suggests that one with three fingers with near normal length, near normal sensation, and a functioning thumb would constitute an “acceptable hand”. This is a useful starting point to consider the assessment and management of a mangling hand injury. An injury resulting or potentially resulting in a hand with a function less than an “acceptable” hand would be a mangling injury, or what the author terms a “major hand injury”.

ASSESSMENT AND INITIAL DECISION MAKING

The initial decision making and first surgery are critical in determining the final outcome of the patient. Ideally, the initial management and surgery should be done by the surgeon who will ultimately perform the reconstruction.

Key points in the history include the hand dominance, time of injury, mechanism of injury, previous hand injury or surgery and functional status of the limb, last meal and events leading up to the injury.

In the usual scenario, the hand surgeon is usually consulted after the patient has been assessed at the emergency department and the general condition stabilized. The surgeon should ascertain that the patient is stable. He should also be aware of any other injuries sustained by the patient, as this has bearing on subsequent treatment. The severity of the initial injury is often but not invariably obvious on first inspection. The severity of the injury may be underestimated in crushing and degloving injuries where the overlying skin envelope appears intact on first look [Figure 1]. A history of the mechanism of injury, for example, the crushing by a heavy object would suggest to the clinician a potentially severe injury.

Figure 1

The apparently intact skin masks the severe crushing injury to the hand and forearm. The clues are the extensive swelling in the hand, the ruptured muscles seen in the first web, and the injury marks on the skin.

The injured limb should be examined and proper photographs [Figure 2] taken to document the injuries. Circulation, sensation and motor function should all be assessed. Plain radiographs with the appropriate views should be done as required. It is not always possible to do a thorough examination or obtain a good plain radiograph at the initial setting. The examination and plain radiographs should be repeated on the operating table after anesthesia if necessary.[5] The availability of intra-operative fluoroscopy will obviate the need to repeat the radiographs. If there are amputated parts, they should be preserved properly,[6] kept with the patient and brought to surgery. At initial assessment, no tissue should be discarded, as there may be potential for replantation or use for biological “spare parts”.

Figure 2

A high quality photograph provides the best documentation of such complex injuries. This is best done on the operating table. Note the skin markings over the distal forearm for the superficial veins in preparation for vein graft harvesting. This should be done before exsanguinations of the limb and inflation of the tourniquet

After the assessment is done, initial treatment should be instituted. It is widely accepted antibiotics should be started to prevent infection, although robust data for this is still lacking.[78] The risk of infection in vascular compromised and contaminated tissue is high.[9] The development of infection will prolong treatment and may compromise the outcome. The antibiotics chosen should be broad spectrum and adjusted for specific needs. The length of treatment of antibiotics is also controversial, and best decided by the treating surgeon. The tetanus toxoid status of the patient should be checked and the toxoid given if necessary.

DECISION POINTS

After the physical examination and review of the radiology, the surgeon should have a plan with the ultimate outcome in mind. A clear plan provides a road map for the surgeon, treating team and patient to follow. Some modifications may be necessary as the clinical course progresses.

The key decisions to be made involve the following considerations:

A determination of what needs to be discarded, either due to contamination, unsuitability for salvage or lack of ultimate functional contribution. This decision may be modified during the initial exploration. For example in the thumb, shortening until the interphalangeal joint has minimal functional consequence.[10]

A rule of thumb useful to help decide if a digit should be salvaged is that if more than two tissues in the digit have a defect that needs replacing, amputation should be considered.

The potential for sensory preservation, recovery or reconstruction in the limb. Sensation and dysesthesia are often more important than length.

The necessity and suitability of any parts for replantation or for use as spare parts.[1112]

Apart from thumb amputations, the loss of a single digit does not affect ultimate hand function. In a study of surgeons (183 in total) who had undergone partial or total digital amputations,[13] including 15 who had partial thumb amputations at the metacarpophalangeal joint, all except 4 were able to continue to do surgery.

What repair or reconstruction is necessary for each of the tissues involved:

Bone and joint. Considerations include debridement, need for shortening, fixation technique, fusion and the need for bone grafting.

Vessel and nerve. The need for microsurgical repair and or grafting.

Tendons. The need for repair either primary or grafting. There may also be total loss of the musculotendinous unit, requiring reconstruction by tendon transfer or free muscle transfer.

Skin and soft tissue cover: The need for skin cover of vital structures.

Timing of definitive surgery: This may be either primary reconstruction or a staged procedure

PRIORITIES

Based on the considerations, the priorities for a mangled hand reconstruction are:

A stable and opposable thumb of adequate length (at least up to interphalangeal joint).[10]

At least one,[1415] and preferable two digits[1617] for pinch with the thumb. The digits should have adequate length and mobility to reach the thumb.

Good sensation of the reconstructed hand.

Good skin and soft tissue cover that is durable and facilitates further reconstruction.

Based on these considerations, a plan is formulated with a basic time-line for the surgery. There are different classifications and treatment algorithms published.[418] These can provide a starting point for adaptation to the local context and practice. The basic plan, need for multiple surgeries, rehabilitation and possible complications should be communicated to the patient in a manner suitable to the patient at that time.

INITIAL SURGERY

Effective use of time is crucial to the surgeon facing such injuries. This is particularly so when the limb is devascularized. The time before the patient arrives in the operating room and is anaesthetized should not be wasted. If there is an amputated part, it can be debrided, inspected under the microscope and prepared for reattachment. The equipment including the microscope and instruments should be checked to be available and working.

Once the patient is anaesthetized, a urinary catheter should be inserted. The superficial veins of the upper limb should be marked for possible harvest. In addition, the legs should be prepared for nerve and vein grafts. After surgical draping of the limb, high quality photographs should be taken for the medical record.

The first surgery is critical to the final outcome for the mangled hand. The key goals during this surgery are:

Removal of devitalized tissue

Removal of contamination

Restoring good vascularity to the remaining tissues and replantation as required

Haemostasis

Achieving bony stabilization

Repair and reconstruction of other tissues if the situation is suitable.

All this is done in an efficient and systematic manner to set the stage for a relook and reconstruction.

Surgical removal of devitalized tissues and contamination prevent infection and delineate the necessary reconstruction. Skin and particularly muscle and loose bone fragments, which are devascularized are excised. There may be delayed tissue necrosis and loss, especially in crush and degloving injuries, hence the importance of the relook assessment.

The debridement will start with a surface scrub to remove loose and superficial contamination in the wound. This is done prior to the surgical preparation with cleansing solutions.

Subsequently, the formal debridement of non-viable and contaminated tissue should be done under tourniquet to allow improved vision and limit blood loss. The debridement is done from superficial to deep and reconstruction from inside out.[2] Muscle viability can be assessed by colour, consistency, contractility and bleeding.[19] Copious washing is done after removal of gross contamination to remove debris and bacteria.[20]

The debridement must be completed before starting repair and reconstruction. The decision for primary and staged reconstruction is made depending on multiple factors. Severe contamination (especially with farmyard and biological material), long delay before surgery, poor patient condition, crush and avulsion injuries where the extent of tissue loss is difficult to ascertain at the first surgery, and an inexperienced surgeon are contraindications towards primary reconstruction.[221]

If a staged reconstruction is planned, the first surgery must achieve good debridement, stabilization of the fractures (with temporary or definitive techniques) and a good vascularity of the remaining tissues before the patient leave the operating theatre. The wound can be temporarily covered with a dressing. A negative pressure dressing will help keep the wound milieu optimal and sterile.[22]

REPLANTATION

The development of microvascular surgery has allowed the replantation of digits and more proximal parts of the hand. In the appropriate situation, it allows the salvage of a mutilating injury to achieve an aesthetically pleasing hand with reasonable function.

From an injury point of view, replantation is indicated for:

Thumb amputations

Multiple digit amputations

Hand and proximal amputations

Paediatric amputations

It is relatively contraindicated for single amputations proximal to FDS insertion, multi-segment injuries and avulsion type injuries. Patient factors also need to be considered. For major amputation proximal to the mid-forearm, where there is a large muscle mass, the ischemic time is a key determinant of whether replantation can be safely done. Beyond 6 hours of warm ischaemia, reperfusion syndrome puts the patient at high risk.

The principles of replantation and tricks of the trade have been well described.[2324] The less experienced hand surgeon would do well to be familiar with them. Adequate but not excessive bone shortening will allow primary vessel repair, nerve coaptation and skin closure. The importance of this should not be underestimated. Second, the threshold to obtain and do a vein graft for the arterial reconstruction should be low. This actually reduces the overall time, by removing the time wasted on a poor initial vessel repair. Usually, the microvascular work is done after the bony fixation and tendon repair. However, if the ischaemic time is prolonged in major amputations, the artery can be anastomosed earlier, once the bone fixation is done or a temporary arterial conduit can be performed first.[25]

In special situations, the replantation of digits may not be orthotopic. A heterotopic replantation may be performed, for example, from a finger to an amputated thumb with no part to restore thumb function.[26] This concept can be extended further by performing a pollicization of the index finger to reconstruct thumb function.[27]

FRACTURE FIXATION

Proper reduction and stabilization of fractures prevents further tissue injury, and is the foundation for the rest of the reconstruction and post-operative rehabilitation.[28] There are many fixation techniques for hand fractures, with varying ease and levels of stability.

Single axial k-wire fixation has been advocated as sufficient and fast in digital replantation.[29] A more rigid form of fixation, which does not cross the cross the joint or skewer the tendons enhances the post-operative rehabilitation. Fixation should provide sufficient stability so that the fracture will not collapse either spontaneously or with active unresisted exercise.[30] Some form of loop wire fixation, either in a 90-90 technique,[31] or a single loop with oblique wire for shaft fractures[32] is easy to perform and provides adequate stability. This can be made simpler by shortening of the bone ends when required in revascularization or replantation. Where the fracture end is close to the joint, joint preservation and fixation without crossing the joint is possible with an intra-articular wire fixation technique.[33] Where there is segmental bone and tissue loss with contamination, external fixation provides stabilization and maintains length. With newer low profile plates, plate and screw fixation is a viable alternative.[3435] The newest development in hand fracture fixation is the introduction of specific locking plates for the hand. They are a useful technique for stabilizing complex and communited diaphyseal fractures.[36]

RELOOK SURGERY AND DEFINITIVE RECONSTRUCTION

If staged reconstruction has been planned, a relook surgery should be done within 48–72 hours.[2] This provides an opportunity to reassess the wound for tissue viability and infection.

At this point, definitive reconstruction can be performed if the wound is clean and no further debridement is necessary. If the wound is not ready, regular relook surgery and debridement is performed until the wound is clean with no infection and non-viable tissue.

SKIN AND SOFT TISSUE COVER

Adequate soft tissue cover for the hand is an important aspect of the reconstruction. It not only provides cover for the exposed tissues, but restores the contour and appearance of the hand. Rehabilitation is also facilitated with wound healing. Good skin and soft tissue reconstruction of a mutilating injury also provides a platform for further reconstruction, for example staged tendon reconstruction or toe transfer.

There are many possibilities for soft tissue reconstruction, but the following criteria with help the surgeon choose an appropriate flap:

Skin flaps for the hand. This is cosmetically more pleasing than skin grafted fascial flaps or muscle flaps. It is also more amenable to debulking and thinning. Skin flaps also make it easier to perform further reconstruction like tendon reconstruction.

Thin flaps are chosen where possible, since the skin in the hand is thin.

Distant flaps are helpful to provide soft tissue cover and bulk without sacrificing potential donor vessels, especially if further reconstruction like toe transfers are being planned [Figure 3].

Figure 3

(a) Severe mangling hand injury with loss of four digits except the thumb. (b) An abdominal flap was done for skin cover to preserve the length for future reconstruction. However, the patient did not want any further reconstruction

The hand surgeon should develop his own armamentarium of flaps, so that an appropriate one can be chosen for each situation. In our institution, the common employed flaps for upper extremity reconstruction are: Posterior interosseous[37] and radial forearm flaps, abdominal and groin flaps, free lateral arm[38] and anterolateral thigh flaps.[39]

NERVE AND TENDON REPAIR

Once the wound is ready for cover, nerve and tendon repair or grafting can be done. Standard techniques can be used. Alternatively, nerve and tendon reconstruction may be deferred until good wound healing. If repair or grafting is not possible, reconstruction using tendon transfers, arthrodesis, or free tissue transfers are usually done later.

THERAPY

The hand therapist is a key player in the management of the mutilating hand injuries. Post-operative therapy contributes much to the outcome. Referral is made immediately after the first surgery. This allows an early assessment by the therapist, and early mobilization of the unaffected joints to prevent stiffness. This will proceed on to definitive therapy of the injured part once surgery is completed. The therapist often sees the patient more frequently and for longer periods of time than the physician in the post-operative period. Good communication between the physician and therapist enables optimization of treatment and early management of complications or problems.

SECONDARY PROCEDURES

The need for secondary procedures following a mutilating injury is high. This should be communicated at the outset to the patient to temper expectations and to involve the patient in the treatment process.

Secondary procedures may be planned from the beginning as part of staged surgery. Examples of this include toe transfers and lengthening procedures after initial skin cover of the mutilated hand. However, secondary surgery may be necessary to address specific issues that have developed over the period of treatment. These include joint releases and tenolysis, tendon transfers, web-widening and scar revision surgery.

Tenolysis is a common procedure following such injuries.[4041] The use of continuous local anaesthesia infiltration can reduce post-operative pain and enhance rehabilitation.[42]

PROSTHESES

Following a mutilating injury, the option for provision of a prosthesis after final surgical reconstruction is an important and often overlooked aspect of treatment.[43] In the upper limb, the prosthesis can provide function in terms of grasp, and help restore the patient's body image. Depending on type of prosthesis, the relative contribution to each function varies.

Immediate fitting post-operatively with functional prostheses, like mechanical ones, improves the outcome, compared to waiting more than 30 days.[44] Improvements in technology have improved the functional prosthesis available. A fully articulating myoelectric prosthesis for the hand with a life-like silicone over glove was recently launched. It allows multiple grip patterns, and is also customizable.[45]

The use of an aesthetic prosthesis can improve the patient's body image and encourages the patient to display his hand and use it [Figure 4]. These prostheses can improve hand function, for example by increasing the hand span.[46]

Figure 4

(a) and (b) A customized silicone prosthesis for an index finger amputation. The ring masks the transition between the prosthesis and normal skin.

There are issues with prosthesis use. Acceptance by the patient is important for sustained use. Prostheses are costly to make and require expertise to design and fit, particularly for aesthetic prostheses and partial hand ones. There is also wear and tear, and a need to replace them over time.

OUTCOMES

Outcomes following reconstruction of mutilating injuries are very variable. There are multiple factors influencing the outcome: Injury related, patient, and treatment related.

These complex injuries are very variable in nature. Factors such as the mechanism of injury, level involved, length of ischemia, and the presence of multiple levels of injury will all affect outcome.

The patient is an important, but unchangeable factor in the equation. The age, psychological makeup, and motivation of the patient are all important. The last two is especially in the rehabilitation process and adaptation.

Treatment of course is also an important key to the outcome. Hence, adherence to the principles discussed here can make a big difference to eventual outcome. It is important to realize that treatment begins from the first encounter, through the multiple surgeries and rehabilitation. The medical treatment ends only when both patient and surgeon agree that the result is static, permanent, and the patient has learnt to adapt with the disability.

A standardized assessment system would be helpful for prognostication and assessment of such injuries. Despite a number of hand and upper limb outcome scoring systems developed, they have not been critically shown to be valid, reliable, consistent, responsive or sensitive for use in mutilating hand injuries.[47] As such, the assessment of an experienced surgeon is still the best option for determining the course of action at the initial outset of such injuries.