Mastering Ray Resections: An Intraoperative Guide to Foot Amputations for Oncologic Conditions

Introduction: The Orthopaedic Oncologist's Challenge in Foot Surgery

Alright, team, gather 'round. Welcome to the operating theater. Today, we're tackling a challenging but crucial procedure: a ray resection of the foot. Unlike other areas of the musculoskeletal system, the foot presents a unique and formidable challenge to the orthopaedic oncologist. Its intricate biomechanics, dense compartmentalization, and critical role in bipedal motion mean that any surgical intervention, especially an oncologic resection, demands meticulous planning and execution to preserve function.

The foot, as you know, functions essentially as a tripod, with the first ray, the fifth ray, and the calcaneus forming its primary weight-bearing points. This structure, coupled with the inherent stability of the midfoot's Roman arch, allows for efficient force distribution during gait. When we resect a ray, we disrupt this delicate balance. Resections of the first and fifth rays, in particular, can lead to significant functional alterations. A first ray resection, for instance, often results in a transfer of forces to the lesser metatarsals. These smaller metatarsals are simply not designed to bear the body's full weight, which can manifest as chronic transverse metatarsalgia postoperatively. Conversely, a fifth ray resection is generally better tolerated, with compensation often achieved through orthotics that shift forces medially. Resection of the middle rays, surprisingly, often results in the least functional deficit, primarily causing a narrowing of the forefoot that can be managed with appropriate shoe modifications.

Understanding the Oncologic Landscape of the Foot

Malignant tumors of the foot are rare, and even rarer distal to the metatarsophalangeal (MTP) joints. However, when they do occur, they necessitate a thorough understanding of the disease process and its implications for surgical management. We often encounter benign lesions more frequently, but the principles of wide local excision with adequate margins remain paramount for both.

FIG 1 • A. Distribution of types of amputations for 153 tumors of the foot and ankle (n = 31).

Comprehensive Surgical Anatomy: Navigating the Foot's Complex Architecture

Before we make any incision, let's review the critical anatomy. The foot is a marvel of engineering, with 26 bones, 33 joints, over 100 muscles, tendons, and ligaments, and a dense neurovascular network, all packed into a relatively small space.

Osteology and Biomechanics

• Rays: Each ray consists of a metatarsal and its associated phalanges. The first ray, comprising the first metatarsal and hallux, is the most robust, bearing significant weight, especially during the toe-off phase of gait (up to 50% of body weight). The lesser rays (second, third, fourth) are more slender, while the fifth ray provides lateral stability.
• Arches: The longitudinal and transverse arches, maintained by both osseous configuration and strong ligamentous and tendinous support (e.g., plantar fascia, spring ligament, tibialis anterior/posterior, peroneus longus), are crucial for shock absorption and propulsion. Resecting a metatarsal can compromise this stability.
• Tarsometatarsal (TMT) Joints (Lisfranc's Joint): These joints form the articulation between the midfoot (cuneiforms, cuboid) and the forefoot (metatarsals). Preserving the base of the metatarsal, if oncologically sound, helps maintain the integrity of the TMT articulation and the overall arch structure.

Neurovascular Structures: The High-Stakes Neighborhood

The compact nature of the foot means neurovascular structures are in close proximity to the bones and joints we're operating on.

• Dorsal Foot:
  • Dorsalis Pedis Artery: A continuation of the anterior tibial artery, it runs distally on the dorsum of the foot, giving off the arcuate artery and dorsal metatarsal arteries. It's superficial and easily palpable.
  • Deep Peroneal Nerve: Provides motor innervation to the extensor digitorum brevis and sensory innervation to the first web space.
  • Superficial Peroneal Nerve: Divides into medial and intermediate dorsal cutaneous nerves, supplying sensation to the dorsum of the foot and toes.
• Plantar Foot:
  • Medial and Lateral Plantar Arteries: Terminal branches of the posterior tibial artery, forming the deep plantar arch. These are vital for toe perfusion.
  • Medial and Lateral Plantar Nerves: Branches of the tibial nerve, providing motor innervation to intrinsic foot muscles and sensation to the plantar aspect of the foot and toes. The common digital nerves and their terminal proper digital nerves are particularly vulnerable during web space dissection and are often directly involved or closely adherent to tumors.
• Muscular Intervals:
  • Extensor Tendons: The extensor digitorum longus and brevis tendons run dorsally, inserting into the phalanges. The extensor hallucis longus serves the great toe.
  • Flexor Tendons: The flexor digitorum longus and brevis tendons, along with the flexor hallucis longus, run plantarly.
  • Intrinsic Muscles: Lumbricals and interossei are small muscles located between the metatarsals, critical for toe stability and function. They often need to be transected proximally during a ray resection.
  • Fibular Graft Harvest (Ipsilateral Limb): When harvesting a fibular graft, we utilize the interval between the peroneus longus and soleus muscles. The common peroneal nerve courses around the fibular neck, and the peroneal artery and veins are in close proximity to the fibula itself. Meticulous dissection is paramount to avoid neurovascular injury here.

Surgical Warning: Always identify sensory nerves just beneath the skin. Pull them distally and transect them sharply with a scalpel to minimize the risk of painful neuromas. Common digital nerves and vascular bundles must be identified and ligated proximally if involved or adherent to the tumor pseudocapsule.

Preoperative Planning: The Blueprint for Success

Effective preoperative planning is not just a recommendation; it's a mandate for achieving a successful oncologic outcome and preserving maximal function.

Patient History and Physical Findings

Our patients typically present with pain and a localized mass. This mass might be chronic, small, or appear following an injury. A thorough physical examination is crucial:

• Inspection: Observe both lower extremities, undressed from the knees, for any swelling, skin changes, or obvious deformity. Compare the affected foot to the contralateral side.
• Palpation: Gently and then deeply palpate the mass. Assess its tenderness, mobility (fixed vs. mobile), and consistency. Note any associated warmth or fluctuance.
• Range of Motion (ROM): Evaluate passive and active ROM of the foot and ankle to identify any joint involvement or limitation caused by the tumor.
• Vascular Examination: Palpate the dorsalis pedis and posterior tibial arteries to assess distal perfusion. Document any neurovascular compromise.
• Neurologic Examination: Evaluate motor strength of toe flexors and extensors, and sensation to light touch in all dermatomes. Note any paresthesias, which may indicate nerve involvement.

Imaging and Staging Studies

Preoperative imaging provides the roadmap.

• Plain Radiographs: Anteroposterior (AP), lateral, and oblique views of the foot are standard. If the ankle is involved, include AP and mortise views. These films help assess bony involvement, cortical thickening, periosteal reaction, and overall bone integrity.
  

  
  
  

FIG 2 • A. Benign tumors can show cortical thickening, mimicking a stress fracture. In this case, it was a benign lesion of the second metatarsal.
* Magnetic Resonance Imaging (MRI): This is indispensable for evaluating soft tissue involvement, intramedullary extent of bone tumors, and the relationship of the tumor to neurovascular bundles and tendons. It helps determine the precise level of amputation needed to achieve clear margins.

Surgical Goals and Principles

Our primary goal is always to remove the tumor with adequate oncologic margins while striving to preserve maximal function and achieve a durable, end-bearing stump. This means:

1. Wide Local Excision: Complete removal of the tumor with a cuff of healthy tissue.
2. Sturdy End-Bearing Stump: Achieved by preserving thick plantar skin and adequate soft tissue padding (muscle, fat, tendons) over the bone ends. A long plantar flap is paramount for this.
3. Smooth, Beveled Bone Edges: Prevents painful bony prominences.
4. Myodesis: Anchoring muscle to the bone end helps pad the stump and improve function.

Patient Positioning and OR Setup

For a ray resection, the patient is typically positioned supine on the operating table.

1. Tourniquet Placement: A thigh tourniquet is applied over generous cotton padding on the ipsilateral leg. This provides a bloodless field, which is critical for precise dissection and identification of neurovascular structures.
2. Hip Bump: A small bump (e.g., blanket roll) may be placed proximal to the sciatic notch on the ipsilateral hip. This helps to limit external rotation of the extremity, ensuring the foot remains in a neutral, accessible position throughout the procedure.
3. Fluoroscopy: The C-arm should be positioned to allow for easy AP and lateral views of the foot. This is especially important for confirming osteotomy levels and hardware placement during reconstruction.
4. Surgical Prep and Drape: The entire lower extremity, from the mid-thigh down to the toes, is prepped with an antiseptic solution (e.g., chlorhexidine or povidone-iodine) and draped in a sterile fashion, allowing full access to the foot and ankle, and potentially the ipsilateral fibula if a graft is planned.

Step-by-Step Intraoperative Execution: The Operating Surgeon's Viewpoint

Alright, fellows, let's scrub in. We've got our imaging, our plan, and our patient perfectly positioned. The tourniquet is up, and the field is bloodless.

General Ray Resection Approach

This general approach applies to most ray resections, with specific modifications for the first ray or MTP joint amputations.

1. Incision Planning and Marking:

   • Dorsal Longitudinal Incision: Using a skin marker, we'll draw a longitudinal incision directly over the involved metatarsal, extending from the level of the tarsometatarsal joint distally towards the toe.
   • Plantar Curvilinear Incision: At the metatarsophalangeal joint, the incision will curve plantarly, encompassing the involved toe or metatarsal head. This curvilinear flap is crucial for later reconstruction of the web space and ensuring a durable plantar flap.
   • Long Plantar Flap: Remember our pearl: a long plantar flap provides the best end-bearing stump. We'll ensure this flap is robust and adequately sized.

2. Skin and Subcutaneous Dissection:

   • Initial Incision: I'll take a #10 blade and make our initial incision through the skin, following our markings.
   • Deepening the Incision: We'll deepen this incision through the subcutaneous tissue. Be meticulous here.
   • Sensory Nerve Identification: Just beneath the skin, you'll start to identify the fine branches of the sensory nerves. We need to manage these carefully to prevent painful neuromas.
     • Technique: Using fine forceps, gently grasp the nerve, pull it distally, and then sharply transect it with a #15 blade or fine scissors. This allows the proximal stump to retract into softer tissue, reducing irritation.
   • Flap Elevation: Carefully elevate the skin and subcutaneous flaps, ensuring adequate thickness for vascularity.

3. Tendon and Neurovascular Management:

   • Extensor Tendon Transection: Identify the extensor tendon(s) corresponding to the involved ray. Using a #15 blade or electrocautery, we'll sharply transect these tendons as proximally as possible, ideally near the tarsometatarsal joint.
   • Common Digital Nerve and Vascular Bundle: As we deepen our dissection, especially in the web space, we'll identify the common digital nerve and its accompanying vascular bundle (plantar digital artery and vein).
     • Tumor Involvement: If these structures are clearly involved with the tumor or tightly adherent to its pseudocapsule, they must be ligated proximally using fine absorbable sutures (e.g., 3-0 Vicryl) and then sharply transected.
     • Preservation (if possible): If they are uninvolved and can be safely dissected away from the tumor, we will attempt to preserve them, particularly for adjacent rays.
   • Lumbrical and Interosseous Muscles: These intrinsic muscles lie between the metatarsals. They will need to be transected proximally, exposing the base of the metatarsal.

4. Osseous Resection (General Principles):

   • Exposure: Retract the soft tissues to fully expose the involved metatarsal.
   • Osteotomy/Disarticulation:
     • Oscillating Saw: If a metatarsal shaft resection is planned, we'll use an oscillating saw to transect the metatarsal at the predetermined level.
     • Disarticulation: If the entire metatarsal is to be removed, we may disarticulate it at the tarsometatarsal joint. Preserving the base of the metatarsal, if oncologically feasible, is preferable as it maintains the integrity of the tarsal-metatarsal articulation and the foot's arch.
   • Tumor Excision: The entire metatarsal, along with the adjacent soft tissues (lumbricals, intrinsics, flexor/extensor tendons, and any involved neurovascular structures), is then excised en bloc with the tumor. The dissection is carried distally and plantarward, separating the capsular structures of the MTP joint from the underlying dermis.
   • Bone Smoothing: After resection, use a rasp to smooth and bevel the bony edges. This prevents painful pressure points on the stump.

5. Web Space Reconstruction (Lesser Ray Resections):

   • Capsular Suture: For lesser ray resections, a 0 nonabsorbable suture (e.g., Ethibond or Fiberwire) is placed through the capsular structures of the adjacent metatarsal heads.
   • Closure: Gentle pressure is applied to the tibial and fibular aspects of the foot to close the defect. This suture is then tied, approximating the adjacent metatarsal heads and narrowing the defect between the rays. This helps maintain the forefoot contour and prevents splaying.

First Ray Resection with Autogenous Fibular Graft Reconstruction

This is a more involved procedure, typically reserved for large resections of the first metatarsal where maintaining forefoot integrity is paramount, especially in younger, active patients.

1. Preoperative Planning Specifics: For a recurrent giant cell tumor of the first metatarsal, as shown in TECH FIG 2, meticulous templating of the fibular graft length is crucial. We're aiming to replace about 8 cm of the first metatarsal.
   

   
   
   

TECH FIG 2 • This example shows a recurrent giant cell tumor of the first metatarsal that was treated successfully with a fibular strut graft. The lateral radiograph shows the healed graft 7 years postoperatively.

1. Incision and Flap Creation (First Metatarsal):

   • Anesthesia: This procedure is often performed under epidural anesthesia for prolonged pain control.
   • Incision: A longitudinal incision is made over the first metatarsal.
   • Fasciocutaneous Flaps: We'll create anterior and posterior fasciocutaneous flaps, extending to the level of the second metatarsal anteriorly and posteriorly. The proximal limb of the incision extends beyond the metatarsal-cuneiform joint, and the distal incision extends to the web space between the first and second toes. This provides excellent exposure and allows for a broad-based flap for closure.

2. Tumor Resection (First Metatarsal):

   • Dissection Planes: The resection will follow specific planes:
     • Between the first and second metatarsals.
     • Along the bone of the second metatarsal (to ensure clear margins from the adjacent ray).
     • Through the first metatarsal-cuneiform joint proximally (or an osteotomy just distal to it, if the base can be preserved).
     • Around the first metatarsal, carefully dissecting the flexor hallucis longus tendon.
   • Osteotomy: The distal metatarsal is osteotomized at the condyles (proximal phalanx is often preserved if uninvolved), and proximally, just distal to the joint or through the TMT joint.
   • Tumor Mass Removal: The entire tumor mass, along with the involved first metatarsal and surrounding soft tissues, is removed en bloc.
   • Preservation of Critical Structures: Throughout this dissection, we must meticulously identify and preserve the anterior tibial tendon, peroneal tendons, and anterior tibial vessels. These are vital for ankle and foot function and vascularity.

3. Fibular Graft Harvest (Ipsilateral Limb):

   • Separate Field: This is performed as a separate, sterile procedure, ideally with a separate set of instruments, to minimize tumor seeding risk.
   • Incision: A longitudinal incision is made over the mid-portion of the fibula on the ipsilateral limb.
   • Muscle Interval: We'll dissect through the interval between the peroneus longus (anterior) and soleus (posterior) muscles.
   • Exposure: Retract these muscles to expose the fibula. The intermuscular septum is released using electrocautery.
   • Osteotomy: Using an oscillating saw, we'll remove an 8 to 10 cm segment of the midshaft fibula, matching the length required for the first metatarsal defect.
   • Wound Closure (Fibular Harvest Site):
     • Thorough irrigation of the wound.
     • Repair the peroneal muscles (peroneus longus and brevis) and soleus using absorbable sutures.
     • Place a small drain in the wound, brought out through a separate stab incision.
     • Close subcutaneous tissue and skin.

4. Graft Reconstruction and Fixation (First Metatarsal):

   • Graft Placement: The harvested fibular strut graft is carefully placed within the defect, spanning the distance between the cuneiform and the remaining metatarsal head (or proximal phalanx).
   • Fixation: Fixation is achieved with two small cortical interfragmentary screws (e.g., 2.7 mm or 3.5 mm cortical screws) proximally and distally, ensuring stable compression and alignment.
   • Hallux Positioning: The hallux is maintained in a neutral position throughout the fixation.
   • Bone Grafting: Corticocancellous bone graft (either from the fibular head if available, or allograft/autograft from other sites) is placed around the base and distal osteotomy sites. Fibrin glue can be used for hemostasis and to promote healing.

Metatarsophalangeal Joint Amputation

This is a more straightforward amputation when the tumor is confined to the toe or distal metatarsal head.

1. Incision Planning: A longer plantar flap is planned. The incision is carried out at the level of the metatarsophalangeal joint on the dorsum of the foot.
2. Dissection: Using sharp dissection, expose the MTP joint.
3. Joint Disarticulation: The capsule, collateral ligaments, and flexor/extensor tendons are sharply cut at the level of the joint.
4. Vascular Control: The digital vessels are identified and meticulously cauterized.
5. Amputation: The toe is then removed.
6. Flap Closure: The long plantar flap is brought over the dorsal aspect of the metatarsal head. The skin is repaired using 4-0 nylon sutures in an interrupted fashion, creating a smooth, non-tender, end-bearing stump.

Final Wound Closure (All Ray Resections)

1. Drain Placement: A small suction drain (e.g., 7mm Blake drain) is placed in the deep defect and brought out through a separate puncture wound to prevent hematoma formation.
2. Subcutaneous Closure: The subcutaneous tissue is meticulously closed with 3-0 absorbable sutures (e.g., Vicryl or PDS) placed in an interrupted fashion to obliterate dead space.
3. Skin Closure: The skin is closed with 4-0 nylon sutures, placed in an interrupted fashion. Ensure even tension and good skin edge apposition.

FIG 2 • G. Intraoperative photograph shows tumor resection.

💡 Pearls and Pitfalls

Surgical Incision and Flap Design

Pearls:
* Long Plantar Flap: Always prioritize a long plantar flap. This skin is naturally thicker, more specialized for weight-bearing, and provides superior padding for the end of the stump. It results in a much better end-bearing stump, reducing the risk of painful pressure areas.
* Metatarsal Cascade: For lesser ray resections, strive to maintain the natural cascade of metatarsal lengths as much as possible to preserve forefoot biomechanics. This helps prevent transfer metatarsalgia.
* Web Space Reconstruction: For central ray resections, approximating the adjacent metatarsal heads with a capsular suture helps narrow the forefoot defect and maintain cosmesis and function.

Pitfalls:
* Short Plantar Flap: A short or poorly vascularized plantar flap will lead to wound dehiscence, necrosis, and a non-functional, painful stump.
* Inadequate Margins: The primary goal is oncologic resection. Never compromise margins for the sake of preserving length or cosmesis. If the tumor is close to the planned incision, consider extending the incision or re-evaluating the amputation level.
* Nerve Transection at Skin Level: Transecting sensory nerves directly at the skin level can lead to painful neuromas. Always pull nerves distally and cut them sharply, allowing the proximal stump to retract into soft tissue.

Intraoperative Challenges and Salvage

Pearls:
* Bloodless Field: A tourniquet is essential. It allows for precise identification of neurovascular structures and clear visualization of tumor margins.
* Meticulous Hemostasis: Even after tourniquet release, ensure all bleeding vessels are cauterized or ligated. Hematoma formation can lead to infection and wound complications.
* Fluoroscopic Guidance: For bone resections and graft fixation, intraoperative fluoroscopy is invaluable for confirming osteotomy levels, alignment, and hardware placement.
* Separate Instruments for Graft Harvest: When performing an autogenous fibular graft, use a separate set of instruments for the harvest site to prevent potential tumor cell seeding from the primary tumor site.

Pitfalls:
* Neurovascular Injury: The foot is dense with nerves and vessels. Inadvertent transection of a major artery (e.g., dorsalis pedis, plantar arteries) can compromise flap viability. If this occurs, immediate repair by a microvascular surgeon may be necessary, or the flap design may need to be revised. Nerve injury can lead to debilitating pain or loss of sensation/motor function.
* Inadequate Bone Resection: Leaving behind tumor-involved bone will lead to recurrence. Always confirm margins with intraoperative frozen sections if there's any doubt.
* Bone Fracture During Graft Harvest: Excessive force or poor technique during fibular osteotomy can lead to an iatrogenic fracture, compromising the graft. Always use a sharp oscillating saw and protect surrounding soft tissues.
* Graft Malposition/Malunion: Improper alignment or fixation of a fibular graft can lead to nonunion, malunion, or biomechanical instability. Ensure rigid fixation and appropriate positioning.

Wound Healing Complications

Pearls:
* Local Wound Care: Meticulous wound care with appropriate dressings (e.g., non-adherent, absorptive) is critical. Keep the wound clean and dry.
* Elevation and Non-Weight Bearing: Postoperative elevation reduces swelling, and strict non-weight bearing protects the wound, especially in the early healing phase.
* Oral Antibiotics: For superficial infections, a short course of oral antibiotics (e.g., cephalexin, clindamycin) is usually sufficient.

Pitfalls:
* Skin Flap Necrosis: This can occur due to inadequate vascularity, excessive tension, or hematoma.
* Salvage: If necrosis is superficial, local wound care may suffice. For full-thickness necrosis, aggressive surgical debridement of devitalized tissue is required. Depending on the size and location, a skin graft (split-thickness or full-thickness) or local flap may be necessary to achieve wound closure.
* Deep Infection: A limb-threatening complication.
* Diagnosis: Signs include persistent pain, fever, erythema, purulent discharge, and elevated inflammatory markers (ESR, CRP). Early diagnosis is crucial.
* Salvage: This requires immediate

Additional Intraoperative Imaging & Surgical Steps

REFERENCES

• A cosmetic toe prosthesis may be used if the patient desires one, but it has no functional purpose.

• Ray resection outcomes depend on the number of rays amputated and whether the first ray is involved. A ray resection of the second, third, fourth, or fifth metatarsal does not need shoe modification with a molded insert or filler. Generally, ordinary store-bought shoes that are wide and have adequate cushioning are worn.

• A first ray resection affects the remaining foot function because of loss of the windlass mechanism. Reconstruction of the first ray would prevent this problem.

• Removal of two central rays will leave a narrower foot and shoewear problems.

• Patients with a metatarsal ray or transmetatarsal amputation have better outcomes than patients with a Syme amputation. 4

• Bugnone AN, Temple HT, Pitcher JD. Low-grade central osteosarcoma of the foot and ankle: radiographic and pathologic features in two patients: case report and literature review. Foot Ankle Int 2005; 26:494–500.

• Choong PF, Qureshi AA, Sim FH, et al. Osteosarcoma of the foot: a review of 52 patients at the Mayo Clinic. Acta Orthop Scand 1999; 70:361–364.

• Chou LB, Malawer MM. Analysis of surgical treatment of 33 foot and ankle tumors. Foot Ankle Int 1994;15:175–181.

• Greene WB, Cary JM. Partial foot amputations in children: a comparison of the several types with the Syme amputation. J Bone Joint Surg Am 1982;64A:438–443.

• Hattrup SJ, Amadio PC, Sim FH, et al. Metastatic tumors of the foot and ankle. Foot Ankle 1988;8:243–247.

• Kirby EJ, Shereff MJ, Lewis MM. Soft-tissue tumors and tumor-like lesions of the foot: an analysis of eighty-three cases. J Bone Joint Surg Am 1989;71A:621–626.

• Murari TM, Callaghan JJ, Berrey BH Jr, et al. Primary benign and malignant osseous neoplasms of the foot. Foot Ankle 1989;10:68–80.

• Seale KS, Lange TA, Monson D, et al. Soft tissue tumors of the foot and ankle. Foot Ankle 1988;9:19–27.

• Sundberg SB, Carlson WO, Johnson KA. Metastatic lesions of the foot and ankle. Foot Ankle 1982;3:167–169.

• Wetzel LH, Levine E. Soft-tissue tumors of the foot: value of MR imaging for specific diagnosis. AJR Am J Roentgenol 1990;155: 1025–1030.

• Wu KK, Guise ER. Metastatic tumors of the foot. South Med J 1978; 71:807–812.