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Intercalary humeral excision and allograft reconstruction with vascularised fibula (the Capanna technique)

    Overview

    Learn the Intercalary humeral excision and allograft reconstruction with vascularised fibula (the Capanna technique) surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Intercalary humeral excision and allograft reconstruction with vascularised fibula (the Capanna technique) surgical procedure.
    Enchondromas are intramedullary neoplasms made of well-differentiated hyaline cartilage. The exact incidence is unknown as the majority are asymptomatic and discovered incidentally. Enchondromas only occur in bones that pre-formed in cartilage. The commonest location is the tubular bones of the hand followed by the femur and humerus. Radiographically, enchondromas can be very large with consequent expansion of the bone, and thinning or complete loss of the cortex.
    Multiple enchondromas are rare. In the case of Ollier’s disease, multiple enchondromas may be found within the hand of one limb, or have a much wider, hemisomic distribution, or affect the entire body with a hemisomic prevalence. The disease is non-hereditary and sporadic. It most commonly affects the tubular bones of the hand or foot. In the case of Maffucci syndrome, multiple enchondromas are associated with multiple cutaneous or deep haemangiomas; the presence of haemangiomas may be identified radiographically as phleboliths. Histologically, the enchondromas appear more cellular than solitary enchondromas, with more proliferative histological potential.
    Transformation to a secondary chondrosarcoma is seen in both these conditions. In Ollier’s, this may occur in 20-40% of patients whilst in Maffucci, this is much more common and is likely to be greater than 50%. Malignant transformation may be heralded by an increase in size of a lesion or the development of symptoms, typically pain. Both conditions are associated with an increased risk of extra skeletal malignancies such as breast, liver, ovarian and CNS tumours.
    The indications for imaging and biopsy of enchondromas in the context of Ollier’s disease is the clinical suggestion of malignant transformation i.e. pain or increase in size. In this case the patient had previously sustained a pathological fracture with resultant deformity and continued to have painful symptoms and dysfunction after fracture union. A biopsy described features consistent with a benign cartilage neoplasm, but recent evidence has questioned the validity of pre-operative biopsy in determining grade in cartilage tumours (https://online.boneandjoint.org.uk/doi/abs/10.1302/0301-620X.100B5.BJJ-2017-1243.R1).

    Indications

    Indications:
    The indications for excision of an enchondroma are the clinical, pathological or radiological suspicion or malignant transformation. Relative indications may include recurrent fracture and resultant deformity, as in this case.
    Symptoms & Examination:
    Malignant transformation of enchondromas may cause pain and swelling, difficulty weight bearing in the lower-limb and dysfunction. Examination may reveal localised pain, deformity, bony hard swelling and limitation of motion. Neurological or vascular compromise would be highly unusual and more suggestive of a rapidly enlarging malignancy rather than a benign or slow growing low-grade chondrosarcoma.
    Investigations:
    Pre-operative imaging includes radiographs and MRI . If malignant transformation is proven after pre-operative biopsy then staging for a chondrosarcoma mandates chest CT and whole-body skeletal staging with bone scintigraphy or MRI. There are no serological investigations relevant to this diagnosis.
    Operative Alternatives: In this case and intercalary resection and reconstruction, though more surgically challenging, was selected to preserve the gleno-humeral and ulno-humeral joints to maximise long-term function in an adolescent patient. Alternatively, joint sacrificing solutions may include proximal humeral allograft-prosthetic composite reconstructions or proximal humeral endoprosthetic reconstructions. It is believed that if good osseointegration is achieved and the joints are preserved, then function will be preserved; the functional outcomes with proximal humeral endoprosthetic replacements are significantly worse.
    Non-Operative Alternatives: There are no medical therapies available for the treatment of benign cartilage tumours nor chondrosarcomas.
    Contraindications: Medical co-morbidities inconsistent with major surgery.

    Setup

    The patient is positioned supine under general anaesthesia with supplementary supraclavicular blocks and intravenous antibiotic prophylaxis (Fluxloxacillin and Gentamicin) as per local antimicrobial protocols.
    An arm table is positioned level with the shoulder to rest the ipsilateral arm doing the procedure.
    Alcoholic skin preparation and incision Ioban drapes are used to cover the surgical field. The limb is isolated using sterile drapes.
    Fluoroscopy is available throughout.
    A second plastic surgical team are prepped to harvest the fibula autograft and perform the microvascular anastomosis.

    Operation – 1

    Pre-operative AP radiograph showing expansion of the proximal humeral meta-diaphysis with central popcorn-like calcification and cortical thinning medially in keeping with a large enchondroma or possibly a low-grade chondrosarcoma. There is evidence of deformity in the humerus in keeping with previous healed fracture.

    Lateral pre-operative radiograph of the right humerus, again showing expansion of the proximal meta-diaphysis with mineralisation consistent with a cartilage tumour and deformity at the level of the tumour, consistent with a healed fracture. The deformity has caused (axial plane) limb shortening and clinically involves the sagittal, coronal planes also.

    T1 coronal MRI scan showing the humeral head and the malunion below the surgical neck of humerus and the low signal (Ct) cartilage tumour at this level in the medial proximal humerus with further low signal (F) foci in the bone in keeping with speckles of calcification from a cartilage neoplasm.
    Lateral to the tumour and malunion, between the (D) deltoid muscle and the humerus is the fat plane in which the anterior branch of the axillary nerve lies. This nerve accompanies the posterior circumflex humeral artery (branch of the axillary artery) through the quadrangular space, and supplies motor innervation to deltoid, teres minor and (in some cadaveric studies) long head of triceps.
    The quadrangular space is bound by: the teres minor above, teres major below, long head of triceps medially and the humeral shaft laterally.

    T2 weighted coronal MRI scan highlighting the areas of high-signal (Ct) cartilage tumour at the level of the healed malunited fracture of the proximal humerus. To excise the tumour en-bloc for optimal oncological results, the meta-diaphysial section distal to the humeral head to below the (F) foci of cartilage must be resected to obtain clearance of all lesional tissue. If this represents a low-grade chondrosarcoma there remains a possibility of small areas of higher grade disease; consequently wide en-bloc resection is advocated to minimise the risk of locally recurrent chondrosarcoma.

    Skin preparation and draping.The skin is prepared with alcoholic chlorhexidine and the upper limb isolated with drapes. The arm is rested on an arm table.
    The skin incision for a deltopectoral approach has been marked and the deformity in the proximal humerus is evident with a bulge consistent with the malunited previous fracture and cartilage tumour.

    Mark the landmarks for the deltopectoral approach.The landmarks for the deltopectoral approach are from the coracoid process (1) down across the deltopectoral interval (2) and along the humerus down to the lateral border of the biceps tendon (3) at the elbow joint.

    Isolate the surgical site with incisional drapes.The axilla is isolated with Ioban incisional drapes, followed by the remainder of the upper arm to the elbow. Bandages isolate the hand and forearm.

    The deltopectoral skin incision begins proximally and is deepened using diathermy through the subcutaneous tissues fat to expose the deep fascia.Once through the skin and fat layer in this slender patient, the protruding cartilage tumour is immediately apparent beneath the deep fascia.

    The cephalic vein is identified as it runs from distal to proximal and once mobilised allows access to the deltopectoral interval.The cephalic vein usually lies within a small fat stripe between the two muscles, but is usually easiest to identify distally and trace proximally in the subcutaneous fat. Identification of the cephalic vein is critical to identify the inter-nervous plane between the axillary nerve (deltoid) and the medial & lateral pectoral nerves (pectoralis major).
    The pectoralis major has two heads: the clavicular head supplied by the lateral pectoral nerve C5-6 and the sternal head supplied by the medial pectoral nerve C7-8.

    It can be seen the (Cv) cephalic vein is very small in this patient and is marked by the tips of the scissors. This needs to be preserved in case it is required for the vascular anastomosis for the fibula autograft later.
    The protruding (Ct) cartilage tumour is seen just to the right of the scissors, immediately beneath the deep fascia in the upper arm.

    Dissection of the cephalic vein is continued proximally towards the coracoid process, progressively mobilising the vein.The cephalic vein runs the length of the surgical wound. Care is taken to avoid damage to the cephalic vein by ligating any muscle tributaries. The vein can be taken medially or laterally, whichever appears easier.

    The deltopectoral plane is deepened onto the humerus.The deltopectoral interval, marked by the cephalic vein, is now dissected using scissors (or blunt digital dissection usually) to deepen the incision through the muscle layer down to the proximal humerus beneath. There are no structures at risk but it can sometimes be tricky to stay in the deltopectoral groove rather than stray into dissecting between muscle fibres of the anterior deltoid.

    Release anterior deltoid off the humerusThe anterior portion of the deltoid distally is dissected off the cartilage tumour using diathermy leaving a cuff of normal tissue on the tumour as a surgical margin.
    The anterior branch of the axillary nerve lies 4-6cm distal from the lateral edge of the acromion, depending upon the size of the patient, between the humeral neck and the deltoid muscle and is at risk with this step. To minimise this risk, the tendinous insertion of deltoid is initially released off the humerus greater than 6cm distal to the acromion, away from the nerve.

    The (DPI) deltopectoral interval has been developed down to the bone.
    The bulge of the (Ct) cartilage tumour can be seen at the centre of the clinical photograph, distal to this the (B) biceps muscle can be visualised at the distal portion of the wound.

    The dissection continues distal to the deltoid insertion and lateral to biceps to expose the humeral shaft.The (D) deltoid insertion has released off the humeral (Ct) cartilage tumour just lateral to the (B) biceps muscle as shown; this is occasionally required for this exposure for trauma but mandatory in oncological resections. This is a relatively avascular plane but crucially taking the biceps laterally protects the musculocutaneous nerve that runs deep and medial to biceps. This nerve arises from the lateral cord of the brachial plexus, accompanies the axillary artery before piercing the coracobrachialis muscle and then lies between brachialis and biceps on the medial side of the upper arm. It then exits the anterior compartment of the forearm by piercing the deep fascia lateral to the biceps tendon to become its terminal branch the lateral cutaneous nerve of the forearm approximately 2cm proximal to the elbow joint. Injury to the musculocutaneous nerve would cause motor loss to the coracobrachialis, medial half of brachialis and biceps and sensory loss to the lateral forearm.

    Incise the clavipectoral fascia lateral to the conjoint tendon Once the interval between (D) deltoid and (P) pectoralis is deepened the layer beneath this muscular interval is the (Cpf) clavipectoral fascia. Proximal dissection continues through the (Cpf) clavipectoral fascia with the McIndoe’s scissors underneath prior to incision with diathermy.
    Incise the clavipectoral fascia lateral to the conjoint tendon and (C) coracoid process. The (Co) coracobrachialis muscle can just be seen, deep to the retracted pectoralis and arising from the coracoid process. We incise the fascia lateral to this muscle to avoid damaging the musculocutaneus nerve as described earlier.

    Once deep to the clavipectoral fascia Identity the coracoid processThe (C) coracoid process is exposed at the base of the wound with the conjoint tendon of the coracobrachialis & short-head of biceps running to the coracoid process (not visible). The retracted (D) deltoid and the (Pm) pectoralis major attaching to the (Ct) cartilage tumour are shown, either side of the deltopectoral interval we have developed.

    A ruler is used to measure from the top of the humeral head to the first osteotomy site.

    Measure the osteotomy levels to guide extent of dissection.
    The ruler is then used to measure from the proximal to the distal osteotomy site for the intercalary resection of the cartilage tumour. This helps to guide how much dissection proximally and distally is required to excise the tumour.

    Elevating the residual anterior deltoid off the humeral shaft facilitates wider exposure of the humerus and its tumour.With the arm rotated internally, further dissection lateral to the surgical neck of humerus occurs. Again care is taken to avoid damage to the anterior branch of the axillary nerve which lies between the (D) deltoid muscle and the humeral neck. This is necessary to facilitate excision of the segmental meta-diaphysial section of humerus containing the tumour and isn’t routine for a deltopectoral approach.

    Dissect pectoralis major off the humerusDissection around the tip of the protruding (Ct) cartilage tumour medially with an artery clip placed underneath the (Pm) pectoralis major insertion, which here is abnormal due to the deformity and tumour.
    A plane has been developed between the bone and the pectoralis major tendon prior to incision leaving a cuff of normal tissue as a surgical margin on the tumour.

    Immediately following dissection of the (Pm) pectoralis major off the humeral (Ct) cartilage tumour, the peak of the tumour shown on the pre-operative X-rays and MRI is visible and medial dissection of the humerus is now possible (B) Biceps and (D) deltoid are also visible distally and proximally.

    Divide the long-head of biceps tendonHaving released the pectoralis insertion and the clavipectoral fascia, the (LHB) long-head of biceps tendon is now visible and has been elevated from the base of the wound. Stay sutures are placed into the tendon and it is incised proximally for re-attachment later.

    Divide the latissimus dorsi tendonThe artery clip is placed underneath the the latissimus dorsi tendon on the medial side of the proximal humerus and stay sutures are placed into this tendon before it is divided off the humerus.

    Divide the teres majorDiathermy is now used to cut the (TM) teres major tendon which inserts onto the proximal humerus and is in an abnormal position due to the previous malunion through the cartilage tumour.
    Remember, care is required as this forms the inferior border of the quadrangular space. It also forms the superior border of the triangular interval, which contains the radial nerve and profunda brachii. The other borders are the long head of triceps medially and the humeral shaft laterally.

    Operation – 2

    Mark the osteotomy sites on the exposed humerusA diathermy mark has been made on the surgical neck of humerus to mark the proximal osteotomy and the distal osteotomy is being measured and checked.

    The distal osteotomy is made first using a 1.27mm blade with an oscillating saw.Sterile saline is dripped onto the saw blade to reduce heat, to minimise thermal necrosis which may impede osseointegration of the allograft and autograft with the host bone. Retractors are placed behind the humerus to avoid damaging the radial nerve running posteriorly between the lateral and medial heads of triceps.

    The osteotomy is complete and a Homan’s retractor is used to elevate the proximal fragment.

    Release triceps off posterior humerusUsing the mobility of the glenohumeral joint to distract the proximal humeral shaft out of the wound, diathermy is used to release the lateral head of (T) triceps muscle from the posterior aspect of the humeral shaft. This dissection of the triceps off the posterior humeral shaft is performed under tension and with diathermy to minimise risk to the radial nerve which lies between the lateral and medial heads of triceps after penetrating the triangular interval.

    Dissection has now reached the capsule on the medial and posterior aspect of the glenohumeral joint, which is signified by the white capsular tissue inserting onto the bone, this is neither incised nor released.

    The proximal osteotomy level is double checked before the osteotomy is performed.

    An oscillating saw is used to complete the proximal osteotomy again using sterile saline dripped onto the bladeAgain sterile saline is dripped onto the oscillating saw blade to reduce thermal necrosis to the residual bone when the proximal osteotomy is made. Again retractors are placed carefully to prevent the saw blade damaging the soft-tissues and in particular the radial and axillary nerves posteriorly.

    Excise the tumourThe cartilage tumour has now been excised and is lifted out of the wound. You can see the deformity in all three planes and the enlargement of the humeral shaft due to the cartilage tumour inside and also the protruding segment anteriorly were the pectoralis major tendon inserted. Perhaps the pull of this strong tendon explains this odd deformity?

    Fibula autograft harvested by second surgical teamA longitudinal lateral incision is made in the line of the fibula and once through fat the fascia incised over the peroneal compartment.

    The fibula is osteotomised 8cm proximal to the lateral malleolus with its periosteum preserved.The peroneal muscles are released off the periosteum. If the osteotomy is too distal then the strong syndesmotic ligaments stabilising the distal tibia-fibular articulation risk being compromised.

    Sub-periosteally dissect the entire fibula shaftThe entire fibula shaft has now been dissected on the lateral aspect and the tourniquet is released to identify any bleeding points to help achieve haemostasis.

    The fibula is osteotomised and dissected with the anterior tibial vessels carefully kept with the fibula graftFollowing osteotomy of the fibular proximally the fibula is gradually swung out of the wound distally to proximal with careful ligation of all branches of the anterior tibial artery and vein preserved.

    Prepare the allograftThe proximal humeral allograft is shown on the back table and as 10cms of diaphysis are required, the humeral head and tuberosity are to be excised and a marker pen is used to mark the osteotomy site.

    The allograft is osteotomised on the back table, taking care not to desterilise the drapes.

    Trial the prepared cut allograftThe allograft is slotted into the wound bridging a gap between the proximal humerus and the distal humeral shaft and a 1.6mm K-wire is used to temporarily fix the allograft to the humeral head. Assess for soft-tissue tension. Due the pre-operative limb-shortening I have deliberately lengthened the humerus slightly to improve the limb-length discrepancy.

    Trial the Philos plateA long philos plate is placed onto the reconstructed humerus and a K-wire is placed through the uppermost hole of the re-attachment plate to confirm the correct positioning of the plate on the humeral head.
    If the plate is positioned too proximally it can cause acromial impingement in abduction. Further K-wires are used to temporarily fix the plate onto the distal humeral shaft. Fluoroscopy is used to confirm satisfactory alignment.

    Prepare the recipient vessels in the arm to receive the vascularised fibula graftFollowing removal of the allograft and plate, the profunda brachii vessels are dissected and slooped for later vascular anastomosis with the vascularised fibular graft.

    Trim the fibula graft 3cm longer than the allograftThe 10cm allograft is measured against the resected vascularised fibular and the fibula is marked to be shortened to leave the fibular approximately 3cms longer than the allograft. The protruding fibula will be impacted into the medullary cavities of the residual humeral head and distal humeral shaft to optimise graft healing.

    Ream the allograft humeral medullaThe medullary cavity of the allograft is reamed out using sequential power reamers sufficient to pass the fibula graft inside the allograft shell.

    Cut a channel in the allograft humerus for the fibula vesselsA slot is created using a high-speed burr to enable the anterior tibial vessels supplying the vascularised fibula graft to be anastomosed to the donor site without damage or compression which might compromise the vascularity ad therefore healing of the graft. This reduces the torsional strength of the allograft but is necessary for rapid graft incorporation.

    Insert the fibula inside the allograft shellAfter trimming of further muscle from the vascularised fibula, the fibular graft is pushed inside the allograft forming a hotdog with the fibular being longer than the allograft at each end to be pushed inside the distal humerus and proximal humeral head.

    Reduce the allograft humerus into the proximal humerusThe allograft is pushed inside the medullary cavity of the humeral head. The recipient brachial vein is visible at the base of the wound as shown.

    Microsurgical anastomosis to vascularise the fibula and allograft.After the fibula tip has been wedged inside the humeral head, the vascular anastomosis is performed between the recipient vessels and the anterior tibial vessels of the donor fibular graft. This is performed using microsurgery by the plastic surgical team.

    Osteosynthesis of the vascularised fibula with allograft shellAfter docking the distal humerus with the allograft the previously selected plate is applied to the reconstructed humerus as shown, four locking screws are placed into the humeral head, two unicortical screws into the allograft and further screws placed into the distal humeral shaft.
    Care is taken to optimise rotational alignment between the humerus and forearm, using the long-head of biceps stump and rotator interval as a reference for neutral rotation proximally.
    For a comprehensive review of the features and application of the Synthes plate read https://www.orthoracle.com/library/open-reduction-and-internal-fixation-of-proximal-humeral-physeal-fracture-using-synthes-philos-plate/

    In external rotation, the reconstruction is visualised and medially the (VA) vascular anastomosis can be seen with engorgement of the vein seen at the tip of the bone lever.

    Operation – 3

    The (LHB) long-head of biceps is tenodesed to the humeral head and plate. The (D) deltoid is sutured to the (Pm) pectoralis major tendon to cover the plate and grafts.The latissimus dorsi and teres major are not reattached to the humeral reconstruction for fear of compromising the vascular anastomosis.

    Deep wound closure to cover the plate and graftsAfter the deltoid and pectoralis tendons have been sutured together, the allograft and plate have been covered as seen. This helps to reduce the risk of infection.

    The wound is now closed in layers with interrupted 2.0 vicryl and a subcutaneous monofilament absorbable suture.

    Skin closureSterile tissue glue is applied to the wound to seal it and the drain is sutured in place.

    Post-operative radiograph showing the allograft and plate with good alignment.

    Lateral post-operative radiograph shows the fibula autograft inside the medullary cavity of the residual distal humerus.

    Post Operative

    Distal neurovascular observations
    IV Antibiotics 24hours (flucloxacillin)
    Poly-sling for 6 weeks: passive pendular glenohumeral and elbow exercises until week 6.
    Start active elbow and shoulder motion from week 6
    Removal drain 48 hours
    Routine X-rays post-op
    Repeat X-rays in clinic at 6 week intervals until union
    Await histology results.

    Recommended Reading

    Options for reconstruction of intercalary segmental defects of the humeral metadiaphysis following oncological resection include fresh frozen or irradiated allografts, vascularised fibula grafts, endoprosthetic replacements and extracorporeal irradiation and reimplantation of the resected humerus.
    The Capanna technique was first performed in 1988 and published in scientific literature in 1993 (https://link.springer.com/article/10.1007%2FBF02620523?LI=true). Vascularised fibula reconstructions had previously been used widely for upper and lower limb reconstructions but initially lack the structural bulk of allografts and so are liable to fracture. Allografts have initial strength but suffer from risks of non-union, infection and later graft fractures which have no ability to heal. Therefore combining the allogenicity of a vascularised fibula with the mechanical strength of bulk allograft was thought offer the best of both.
    Li et al. reported seven cases with intercalary humeral Capanna reconstruction without infection nor fracture and the mean time to union for the fibula and allograft were 21 and 26 weeks respectively.The authors reported function results within 95% of normal and cited the vascularised fibula leading to early graft incorporation and rapid rehabilitation for their excellent functional outcomes (https://onlinelibrary.wiley.com/doi/pdf/10.1002/jso.21922). By contrast in a meta-analysis of vascularised fibula reconstructions of the humerus (without allograft shell) reported the same mean fibula graft union time and the most common complications were fracture (11.7%), nerve injury (7.5%) & infection (5.7%)(https://onlinelibrary.wiley.com/doi/pdf/10.1002/jso.25032).

    Reference

    • orthoracle.com

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