Vascular Limb Injuries and Compartment Syndrome

Introduction

Vascular limb injuries and compartment syndrome share a fundamental concern with tissue perfusion — the maintenance of adequate blood flow to the muscle, nerve, bone, and skin of the injured extremity to prevent the irreversible cell death that follows prolonged ischemia. The vascular injury represents the failure of arterial blood delivery to the limb, with consequent ischemia distal to the injury; compartment syndrome represents the failure of microcirculatory perfusion within the muscular compartments because of elevated tissue pressure exceeding capillary perfusion pressure. Both conditions are surgical emergencies with limited windows for successful intervention, with the limb-loss rate rising steeply when treatment is delayed beyond approximately 6 to 8 hours of warm ischemia. The recognition and management of these emergencies is a defining feature of orthopedic and trauma practice, and the orthopedic surgeon’s role in the patient with combined orthopedic and vascular injury — particularly the decision between limb salvage and amputation — represents one of the most challenging judgments in clinical orthopedics. This chapter, the final topic in the trauma section, addresses both conditions and draws on Rockwood and Green’s Fractures in Adults, AO Principles of Fracture Management, Apley & Solomon’s, and Miller’s Review of Orthopaedics.

Vascular Injuries — Mechanisms and Patterns

The principal mechanisms of vascular injury in orthopedic trauma include: Penetrating trauma: Gunshot wounds, knife wounds, glass and similar sharp injuries, and the occasional iatrogenic injury during surgical procedures. The injury may be complete transection (with frank hemorrhage), partial laceration (with continuing or recurring bleeding, sometimes with delayed presentation), or contained injury (with intimal disruption that may produce delayed thrombosis). Blunt trauma with associated fracture or dislocation: The classical orthopedic-vascular combinations include the popliteal artery in knee dislocations (Topic Trauma-26), the brachial artery in supracondylar humerus fractures (particularly in children), the popliteal artery in distal femur and proximal tibia fractures, the brachial artery in elbow dislocations, the subclavian/axillary artery in shoulder girdle injuries, and the iliac vessels in pelvic ring injuries (Topic Trauma-19). Stretch injury: With the vessel pulled beyond its elastic limit, producing intimal disruption with intact adventitia (the classical “intimal injury” with delayed thrombosis), partial laceration, or complete rupture. Crush injury: With direct compression and damage to the vessel wall. Iatrogenic injury: During surgical procedures (including arthroscopic procedures with sharp portal placement and screw or pin placement near vessels), arterial catheterization, and other interventional procedures.

The pattern of vascular injury includes: Complete transection with active hemorrhage (or, in some cases, vasospasm and clot formation that limits the immediate bleeding). Partial transection with continuing or recurring hemorrhage. Intimal disruption with potential delayed thrombosis — the most insidious pattern because the initial vascular examination may be misleadingly normal. Pseudoaneurysm formation: A contained hematoma with persistent arterial communication, typically presenting days to weeks after the original injury. Arteriovenous fistula: Direct communication between artery and vein, often presenting late with bruit, thrill, and limb swelling.

Clinical Assessment of Vascular Injury

The classical “hard” and “soft” signs of vascular injury structure the assessment: Hard Signs Hard signs of vascular injury indicate definite arterial compromise and mandate urgent intervention: • Active pulsatile bleeding: Visible arterial hemorrhage. • Expanding or pulsatile hematoma: Suggests continuing arterial bleeding into a contained space. • Absent distal pulses: Loss of arterial inflow to the distal extremity. • Distal ischemia signs: Pallor, paresthesias, pain, paralysis, poikilothermia (cold extremity). • Audible bruit or palpable thrill: Indicates turbulent flow at the injury site. The presence of hard signs is an indication for immediate operative exploration without further imaging delays. Soft Signs Soft signs indicate the possibility of vascular injury and require further evaluation: • History of significant hemorrhage at the scene. • Diminished but present pulses: May reflect vasospasm, partial injury, or compensated injury. • Peripheral nerve deficit: May reflect proximity of vascular injury to the nerve. • Proximity of wound to major vessel: Anatomical concern even without specific findings. • Unequal pulses or blood pressures between extremities. • Hematoma: Non-expanding hematoma over the course of a major vessel.

The presence of soft signs without hard signs warrants further evaluation with imaging or measurements. The Ankle-Brachial Index (ABI) and Injured Extremity Index The ankle-brachial index (ABI) in lower extremity injury, or the injured extremity index (IEI) (the ratio of pressure at the injured side to pressure at the contralateral uninjured side), is a validated screening tool. An ABI or IEI less than 0.9 has been shown to be highly sensitive (>95 percent) for arterial injury requiring intervention. The measurement is performed with a Doppler probe; the systolic pressure at the most distal palpable or audible pulse is divided by the brachial systolic pressure (for ABI) or the contralateral side (for IEI). Imaging For patients with hard signs or with abnormal ABI: CT angiography (CTA) is the imaging modality of choice in most centers because of its widespread availability, rapid acquisition, and ability to image both bony and vascular structures simultaneously. The sensitivity and specificity for clinically significant vascular injury are both above 95 percent. Conventional angiography is reserved for ambiguous cases or for therapeutic intervention (embolization, stenting). The “operative angiography” performed in the operating room provides real-time information during exploration. Duplex ultrasonography can be useful for evaluation of the more accessible vessels but is operator-dependent and less practical for many orthopedic settings.

Management of Vascular Injuries

Immediate Stabilization Hemorrhage control is the first priority. For external hemorrhage, direct pressure is the principal initial intervention. Tourniquets have regained acceptance for life-threatening extremity hemorrhage, with the lessons learned from military experience and the recognition that prompt tourniquet application is preferable to permitting exsanguination. The tourniquet is applied proximal to the injury, with documented time of application; the maximum recommended duration is approximately 2 hours, although longer durations may be necessary in delayed evacuation. Volume resuscitation follows the principles outlined in Topic Trauma-6 (polytrauma): crystalloid as initial fluid, conversion to blood products with massive transfusion protocol in significant hemorrhage, tranexamic acid within 3 hours of injury, and damage control resuscitation principles.

Operative Management of Vascular Injury The principles of vascular repair in the orthopedic context:

Sequencing with orthopedic fixation: The classical sequence is temporary vascular shunting to restore inflow rapidly, followed by orthopedic fracture stabilization (with external fixation for rapid stabilization providing a stable platform for definitive vascular repair), followed by definitive vascular repair with interposition graft (typically reversed saphenous vein) or primary repair as the injury permits. This sequence — sometimes called the “shunt-fix-repair” approach — allows restoration of inflow within minutes while permitting careful fracture stabilization and meticulous vascular repair. Heparinization of the patient or selective limb heparinization is part of the protocol. Definitive vascular repair is by primary anastomosis when the gap is small and tension- free, or by interposition graft (reversed saphenous vein graft from the contralateral leg being the standard for most peripheral arterial repairs; prosthetic graft acceptable for larger vessels and contaminated wounds where vein graft is inferior). Fasciotomy is routinely performed for vascular injuries with prolonged ischemia time (typically more than 4 to 6 hours) because of the substantial risk of reperfusion-induced compartment syndrome. Adjuncts Anticoagulation is given selectively, balancing the risk of thrombosis at the repair site against the bleeding concerns in the polytrauma patient. Typical protocols use heparin during the operative procedure with conversion to oral anticoagulation or antiplatelet agents postoperatively. Postoperative monitoring by serial pulse checks, ABIs, and Doppler studies identifies recurrent or delayed thrombosis. Re-exploration is performed promptly for any concern about graft thrombosis.

The Mangled Extremity and the Limb Salvage Decision

The mangled extremity — the limb with severe combined injuries to bone, soft tissue, vessels, and nerves — presents the orthopedic surgeon with the most challenging decision in trauma practice: limb salvage versus amputation. The decision incorporates patient factors (age, comorbidities, functional demands, lifestyle), injury factors (severity of bone, soft tissue, vascular, nerve injury), operative factors (availability of microsurgical reconstruction, infrastructure, surgeon experience), and outcome factors (likely time to recovery, expected functional outcome, complication risks). Several scoring systems have been developed to guide the decision: The Mangled Extremity Severity Score (MESS, Johansen 1990) considers four variables: skeletal/soft tissue injury (low energy 1, medium energy 2, high energy 3, very high energy with crush 4), limb ischemia (reduced pulse with normal perfusion 1; pulseless paresthesias 2; cool, paralyzed 3 — doubled if more than 6 hours), shock (systolic BP always >90 mmHg 0; transient hypotension 1; persistent hypotension 2), and age (less than 30 years 0; 30-50 years 1; over 50 years 2). The classical cutoff was MESS ≥ 7 predicts amputation, though the predictive value has been criticized in subsequent series.

Other scoring systems include the Mangled Extremity Syndrome Index (MESI), the Predictive Salvage Index (PSI), and the Limb Salvage Index (LSI). The general finding from contemporary research is that no single score reliably predicts outcomes with sufficient accuracy to drive amputation decisions, and the decision must be individualized based on the full clinical picture. The LEAP trial (Lower Extremity Assessment Project, Bosse et al., 2002), a landmark prospective observational study, found that limb salvage and amputation produced broadly similar functional outcomes at 2 and 7 years, with the principal determinants of outcome being patient socioeconomic factors and psychological state rather than the specific orthopedic treatment. This finding has substantially shaped contemporary thinking about the limb salvage decision, with the recognition that aggressive salvage of marginal limbs may produce worse outcomes than well-performed primary amputation with appropriate prosthetic management. The factors that favor early amputation include warm ischemia exceeding 6 to 8 hours with severe muscle and tissue injury (irreversibly damaged tissue), complete loss of plantar sensation (although this has been controversially used as an absolute indication and may not always indicate poor outcome), severe combined nerve and vascular injury in older patients, and the polytrauma patient where prolonged salvage attempts could worsen overall outcome. The factors that favor limb salvage include preserved sensation, viable proximal muscle, vascular injury amenable to reconstruction, the young patient with strong motivation for limb preservation, and the availability of microsurgical and soft-tissue reconstructive resources.

Compartment Syndrome — Definition and Pathophysiology

Acute compartment syndrome is the clinical condition resulting from elevated pressure within a fascial compartment, with consequent compromise of capillary perfusion and progressive ischemia of the contained tissue (muscle, nerve). The condition is a surgical emergency with limited tolerance for delay — irreversible muscle necrosis and nerve damage develop after approximately 6 to 8 hours of unrelieved compartment syndrome, with permanent consequences (Volkmann’s ischemic contracture, persistent neurological deficit, chronic pain). Pathophysiology The pathophysiology follows a self-perpetuating cycle: Initial insult (fracture, crush injury, hemorrhage, prolonged ischemia with reperfusion) produces accumulation of fluid, blood, or edema within the closed fascial compartment. Increasing intracompartmental pressure rises above the capillary perfusion pressure (typically 25 to 30 mmHg). Capillary collapse occurs, with cessation of perfusion to the capillary beds despite continued arterial inflow at higher pressures.

Tissue ischemia produces cell membrane dysfunction, intracellular edema, and further increase in compartmental pressure — creating the self-perpetuating cycle. Muscle necrosis and nerve injury progress with continuing ischemia, with the rate of damage being faster for nerves than for muscles (nerve damage may occur within 1 to 2 hours of severe pressure elevation; muscle damage begins by 2 to 4 hours and is largely irreversible by 6 to 8 hours). The critical concept is that compartment syndrome can occur without occlusion of major arterial inflow — distal pulses may be preserved while the microcirculation is compromised. Reliance on the presence of pulses to exclude compartment syndrome is a classical pitfall. Specific Risk Factors The principal risk factors for compartment syndrome include: Fractures: Tibial shaft fracture is the most common precipitant (Topic Trauma-27); other high-risk fractures include forearm fractures (with Volkmann’s contracture as the classical end-stage if missed — Topic Trauma-8), distal radius fractures, supracondylar humerus fractures in children, and elbow fracture-dislocations. Crush injuries: Direct soft-tissue compression, particularly with reperfusion after release. Vascular injuries: Particularly with prolonged ischemia and subsequent reperfusion. Tight casts or dressings: External compression that does not accommodate increasing internal volume. Anticoagulation: Increased risk of compartmental hematoma formation. Prolonged surgical positioning: Particularly the supine “lithotomy” position with elevated leg, where compartment syndrome of the well leg (contralateral to the operated side) has been described. Burns: Eschar formation in circumferential burns produces external compression equivalent to a tight cast. Snake bites and other envenomations: With local tissue swelling and bleeding. Bleeding disorders: Hemophilia, anticoagulation excess. Reperfusion after ischemia: Following vascular repair or after release of prolonged tourniquet.

Clinical Diagnosis of Compartment Syndrome

The diagnosis of compartment syndrome is principally clinical, with the classical features that the orthopedic surgeon must recognize:

The 5 P’s (Modified to 6 P’s) The classical mnemonic includes Pain, Paresthesias, Pallor, Pulselessness, Paralysis, sometimes extended to add Poikilothermia (temperature changes). However, this mnemonic is misleading because: Pulselessness is a late sign that develops only when intracompartmental pressure exceeds systolic arterial pressure — by that time, irreversible tissue damage is already established. The presence of pulses does not exclude compartment syndrome. Paralysis is similarly a late finding indicating advanced nerve injury. Pallor is variable and not always present. The Reliable Early Signs The early reliable signs of compartment syndrome are: Pain out of proportion to the apparent injury: The most sensitive and early sign. The patient typically complains of severe pain unresponsive to typical doses of analgesics, with progressive worsening rather than improvement over time. Pain on passive stretch of the muscles within the affected compartment: For example, passive extension of the toes produces pain in the deep posterior compartment of the leg in deep posterior leg compartment syndrome; passive flexion of the toes produces pain in the anterior compartment in anterior compartment syndrome of the leg. Tense, swollen compartment on palpation. Paresthesias in the distribution of the affected nerve: An early sign of nerve involvement. The patient who is alert and examinable can usually be diagnosed clinically through these features. The challenge is the obtunded, intubated, or unconscious patient who cannot report symptoms — in this population, compartment pressure measurement and a low threshold for fasciotomy are essential.

Compartment Pressure Measurement When clinical signs are equivocal or the patient cannot be reliably examined, direct measurement of intracompartmental pressure provides objective information. Methods include: Whitesides technique: A needle is introduced into the compartment with saline filling tubing; the pressure required to displace saline back into the tubing is the compartment pressure. The technique is simple but somewhat imprecise. Slit catheter or wick catheter: More sophisticated indwelling catheters provide continuous monitoring. Solid-state pressure transducer: Specialized devices (Stryker, Synthes) provide rapid and accurate single measurements.

Continuous monitoring: An indwelling catheter connected to a pressure transducer allows continuous pressure measurement, useful in the obtunded patient or postoperative monitoring. The threshold for fasciotomy is debated. The classical absolute threshold was 30 mmHg. The more refined perfusion pressure threshold (Δp = diastolic BP − compartment pressure) of less than 30 mmHg accounts for the patient’s blood pressure and is now generally preferred. Some authors advocate even lower thresholds (Δp < 20 mmHg) in particular settings. The rate of rise of compartment pressure and the duration of elevated pressure are also clinically important — sustained elevation requires more urgent intervention than brief peaks.

Treatment of Compartment Syndrome — Fasciotomy

The treatment of established compartment syndrome is urgent decompressive fasciotomy — release of all the involved compartments through open fascial incisions. The principles are: All compartments must be released: Failure to release any involved compartment defeats the procedure. The surgeon must understand the anatomy and ensure complete release of all compartments in the affected limb segment. The incision must be long enough: The classical “lazy S” or “long S” incision provides full- length decompression of the compartment; “windowing” fasciotomy with short incisions is inadequate. Skin closure should not be attempted at the time of fasciotomy: The compartment must be left open with appropriate dressings; delayed closure or skin grafting is performed when the swelling resolves (typically 5 to 10 days after fasciotomy).

Specific Compartment Anatomy and Approach Leg compartments (4): - Anterior compartment: Tibialis anterior, EHL, EDL, peroneus tertius; anterior tibial artery and deep peroneal nerve. - Lateral compartment: Peroneus longus and brevis; superficial peroneal nerve. - Superficial posterior compartment: Gastrocnemius, soleus, plantaris. - Deep posterior compartment: Tibialis posterior, FDL, FHL; posterior tibial artery and tibial nerve. Leg fasciotomy is performed through the double-incision technique (Mubarak): a lateral incision (between the anterior and lateral compartments, allowing release of both) and a medial incision (releasing the superficial and deep posterior compartments). Each incision is long (essentially the full length of the involved segment), with the fascia of each compartment opened along its length. The deep posterior compartment release requires detachment of the soleus from the medial tibia to allow access. Single-incision techniques have been described (fibulectomy with single lateral incision) but are not the standard approach.

Forearm compartments (3 to 4): - Volar compartment: Includes the superficial and deep flexors and the pronator. - Dorsal compartment: Extensors. - Mobile wad: Brachioradialis, ECRL, ECRB (sometimes considered part of the dorsal compartment). Forearm fasciotomy is performed through the Henry approach (curvilinear volar incision from medial epicondyle, across the antecubital fossa, along the volar forearm, and crossing the wrist crease in a Z fashion) with carpal tunnel release. A dorsal incision is added if needed for dorsal compartment release. Hand compartments (10): Multiple small compartments require careful systematic release through two dorsal incisions (over the second and fourth metacarpals to release the dorsal and palmar interossei), with carpal tunnel release if indicated. Thigh compartments (3): Anterior, posterior, and adductor. Thigh fasciotomy is less commonly required but uses a single lateral incision (releasing the anterior and posterior compartments through fascial windows) with a separate medial incision for the adductor compartment if needed. Foot compartments (9): Multiple compartments including medial, central, lateral, interosseous, and others. Foot fasciotomy uses two dorsal incisions (over the second and fourth metatarsals) with a medial incision if needed. Buttock compartments: Rare site of compartment syndrome but occurs in prolonged immobility with severe pressure injury, hyperflexion injuries, or vascular injury. Decompression requires posterior incisions through the gluteal fascia. Post-Fasciotomy Management Wound management after fasciotomy follows the principles of open wound care: Initial dressing with sterile dressings (saline gauze, foam dressings, or vacuum-assisted closure (VAC) systems). VAC systems are increasingly used because they help draw down the wound edges and prepare the wound for closure. Serial wound evaluation at 24 to 72 hours and at intervals thereafter, with debridement of any necrotic muscle. Delayed primary closure (DPC) at 5 to 10 days as swelling resolves. Skin retraction has often occurred by this time, requiring gradual closure techniques (such as the shoelace closure technique), skin substitutes, or split-thickness skin grafting of the residual wound. Reperfusion injury management: Patients with prolonged compartment syndrome may develop rhabdomyolysis with myoglobinuria and risk of acute kidney injury; aggressive intravenous fluid resuscitation with attention to urine output and electrolyte balance (particularly potassium, calcium, phosphorus) is essential.

Specific Considerations

Crush Syndrome Crush syndrome is the systemic response to prolonged muscle compression, characterized by hyperkalemia, hypocalcemia, rhabdomyolysis with myoglobinuria, and acute kidney injury. The condition was historically described in earthquake victims and bombing casualties (the “Bywater’s syndrome”) and remains a concern in modern disaster medicine and major orthopedic trauma. The principles of management include rapid extrication when possible, aggressive intravenous fluid resuscitation (often 1 L/hour or more) begun before extrication to dilute the released potassium and prevent acute kidney injury, alkalinization of the urine (to reduce myoglobin precipitation in renal tubules), and dialysis when needed for renal failure or severe hyperkalemia.

Tourniquet-Related Compartment Syndrome Prolonged use of a surgical tourniquet (typically over 2 hours) can produce reperfusion- related compartment syndrome of the affected limb. Prevention includes appropriate tourniquet time limits, periodic deflation in prolonged cases, and awareness of the risk.

Compartment Syndrome in the Obtunded Patient The obtunded patient (head injury, intubated and sedated, intoxicated) is at particular risk for missed compartment syndrome because the early sign of pain is not available. Compartment pressure monitoring, high index of suspicion, and low threshold for fasciotomy are essential in this population. Chronic Exertional Compartment Syndrome Chronic exertional compartment syndrome (CECS) is a distinct entity from acute compartment syndrome. The condition affects athletes performing repetitive activity and produces predictable elevation of compartment pressures with exercise, producing pain and dysfunction that resolves with rest. The classical setting is the runner with leg pain that begins after a predictable distance of running and resolves within minutes of stopping. Diagnosis is by dynamic compartment pressure measurement (with measurements before, during, and after exercise; postexercise pressures greater than 30 mmHg at 1 minute or greater than 20 mmHg at 5 minutes are diagnostic). Treatment is elective fasciotomy of the affected compartments, with reasonably good outcomes (60 to 80 percent return to pre-symptom activity level).

Summary and Take-Home Points

Vascular injuries in orthopedic trauma occur most commonly in association with specific fracture and dislocation patterns: popliteal artery in knee dislocation, brachial artery in supracondylar humerus, axillary artery in shoulder injuries, iliac vessels in pelvic ring injuries. The clinical assessment combines hard signs (active bleeding, expanding hematoma, absent pulses, distal ischemia) with soft signs (history of significant bleeding, diminished pulses, peripheral nerve deficit, wound proximity). The ankle-brachial index

(or injured extremity index) less than 0.9 is a sensitive screening tool. CT angiography has become the imaging modality of choice for definitive evaluation. Management of vascular injury follows the shunt-fix-repair sequence in patients with combined orthopedic and vascular injury: temporary vascular shunting to restore inflow within minutes, external fixation for rapid orthopedic stabilization providing a stable platform, definitive vascular repair with interposition graft (reversed saphenous vein) or primary repair, and routine fasciotomy for prolonged ischemia. The mangled extremity decision (limb salvage versus amputation) is among the most challenging in trauma orthopedics. Scoring systems (MESS, MESI, PSI, LSI) provide some guidance but lack sufficient predictive accuracy to drive decisions. The LEAP trial demonstrated broadly similar long-term outcomes between salvage and amputation in marginal limbs, with patient psychological and socioeconomic factors being the principal determinants of outcome. The decision must be individualized based on the full clinical picture. Compartment syndrome is the orthopedic surgical emergency requiring immediate recognition and urgent fasciotomy. The early clinical signs are pain out of proportion to apparent injury, pain on passive stretch, tense compartment, and paresthesias; the late “5 P’s” of pulselessness and paralysis indicate advanced injury and should never be required to make the diagnosis. Compartment pressure measurement with the perfusion pressure threshold (Δp < 30 mmHg) is the objective test when clinical signs are equivocal or the patient cannot be examined. Fasciotomy must release all involved compartments through long incisions, with skin left open and delayed closure or skin grafting at 5 to 10 days. The specific compartment anatomy must be respected: 4 compartments in the leg (double-incision Mubarak technique), 3 compartments in the forearm (Henry approach with carpal tunnel release), 10 compartments in the hand, 9 compartments in the foot, 3 in the thigh. Crush syndrome with rhabdomyolysis requires aggressive fluid resuscitation and renal protection. This chapter concludes the trauma section of the compendium. The chapters that follow turn to the surgical anatomy and approaches that complete the curriculum — beginning with the spine and cervical region and proceeding through each anatomical region with focus on the operative approaches that the orthopedic surgeon must master to perform the procedures described throughout the orthopedic and trauma chapters.