BACKGROUND: Limb salvage following resection of a tumor in the proximal part of the humerus poses many challenges. Reconstructive options are limited because of the loss of periarticular soft-tissue stabilizers of the glenohumeral joint in addition to the loss of bone and articular cartilage. The purpose of this study was to evaluate the functional outcome and survival of the reconstruction following use of a humeral allograft-prosthesis composite for limb salvage.
METHODS: An allograft-prosthesis composite was used to reconstruct a proximal humeral defect following tumor resection in thirty-six consecutive patients at one institution over a sixteen-year period. The reconstruction was performed at the time of a primary tumor resection in thirty cases, after a failure of a reconstruction following a previous tumor resection in five patients, and following excision of a local recurrence in one patient. The mean duration of follow-up of the living patients was five years. Glenohumeral stability, function, implant survival, fracture rate, and union rate following the reconstructions were measured. Functional outcome and implant survival were analyzed on the basis of the amount of deltoid resection, whether the glenohumeral resection had been extra-articular or intra-articular, and the length of the humerus that had been resected.
RESULTS: One patient sustained a glenohumeral dislocation. Deltoid resection (partial or complete) resulted in a reduced postoperative range of motion in flexion and abduction but had no effect on the mean Musculoskeletal Tumor Society score. Extra-articular resections were associated with lower Musculoskeletal Tumor Society scores. All patients had either mild or no pain and normal hand function at the time of final follow-up. The overall estimated rate of survival of the construct, with revision as the end point, was 88% at ten years. There were three failures due to progressive prosthetic loosening that necessitated removal of the construct. Four patients required an additional bone-grafting procedure to treat a delayed union of the osteosynthesis site.
CONCLUSIONS: An allograft-prosthesis composite used for limb salvage following tumor resection in the proximal part of the humerus is a durable construct associated with an acceptable complication rate. Deltoid preservation and intra-articular resection are associated with a greater range of shoulder motion and a superior functional outcome, respectively.
LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.
ORIGINAL ABSTRACT CITATION: “Allograft-Prosthesis Composite Reconstruction of the Proximal Part of the Humerus. Functional Outcome and Survivorship” (2009;91:2406-15).
Limb salvage following wide excision of malignant and benign aggressive tumors of the proximal part of the humerus poses appreciable reconstructive challenges due to bone and soft-tissue loss. Most patients require partial or complete excision of the deltoid, rotator cuff tendons, and/or glenohumeral joint capsule. Such extensive soft-tissue resections threaten the stability and function of the glenohumeral joint. The reconstructive possibilities following proximal humeral resections are limited and include the use of (1) an osteoarticular allograft, (2) a large-segment endoprosthesis, (3) an arthrodesis with an intercalary allograft and/or a vascularized fibular graft, or (4) an allograft-prosthesis composite. Each option can be associated with major complications. Osteoarticular allografts, for instance, can be associated with subchondral collapse and humeral head fracture; unconstrained endoprostheses lack soft-tissue attachments and thus can be complicated by glenohumeral joint dislocation; and a solid arthrodesis is often difficult to achieve and by definition sacrifices glenohumeral motion and its associated functional benefits.
Among the options for limb salvage following tumor resection of the proximal part of the humerus, the allograft-prosthesis composite is a favorable choice that addresses many of the reconstructive challenges of proximal humeral resections: The allograft-prosthesis composite combines the durability of an endoprosthesis and the benefits of an allograft (i.e., restored bone stock and soft-tissue attachments). These soft-tissue attachments, including the rotator cuff and joint capsule, can substitute for the deficient soft tissues of the host and can create a stable, functional construct1.
The extent of resection is classified preoperatively according to the system of the Musculoskeletal Tumor Society (MSTS)2. The decision to perform an intra-articular or extra-articular resection is made during preoperative planning. Radiographic or clinical evidence of joint invasion by the tumor dictates an extra-articular, joint-sacrificing resection. Accurate, focused imaging is essential to plan the resection properly. This often requires magnetic resonance imaging of the shoulder with oblique coronal cuts oriented to assess the involvement of the rotator cuff tendons. A separate magnetic resonance imaging scan of the humerus is needed to identify the distal extent of the tumor and rule out intramedullary skip metastases.
Intra-articular resection involves transection of the rotator cuff tendons and joint capsule. By definition, the glenohumeral joint is not violated during an extra-articular resection, and, thus, the capsule remains intact. On the basis of the presence or absence of a functional deltoid (and axillary nerve), the resection is classified as either a type A or type B, in keeping with the modified classification system of Malawer et al. for proximal humeral resections3.
The patient is placed on the surgical table in the semilateral position with an axillary roll on the down side to prevent brachial plexus injury to the other arm. A longitudinal deltopectoral approach is used and extended across the acromioclavicular joint and down the back of the shoulder along the lateral border of the proximal scapula. The previous biopsy track is excised, leaving an ellipse in continuity with the resected specimen. Typically, this means losing a portion or all of the deltoid. The axilla is exposed by releasing the pectoralis major tendon and osteotomizing the coracoid to retract the conjoint tendon. The musculocutaneous nerve is protected, the biceps is cut, and its tendon is left in the bicipital groove with the tumor. The anterior circumflex humeral vessels are ligated in order to develop the interval between the axillary vessels and the tumor. The posterior circumflex vessels are dissected free or ligated. This allows access to the axillary nerve. If the deltoid can be saved, a reasonable effort should be made to save the axillary nerve without compromising the ability to achieve a wide surgical margin. The latissimus dorsi is cut, and the tendon is tagged. The muscle may be needed as a pedicle rotation flap to provide soft-tissue coverage, especially if the deltoid is sacrificed.
The intra-articular resection is performed in steps. The subscapularis tendon is transected medially, before it becomes confluent with the capsule. The capsule is then opened to obtain a clear view of the joint. The remaining capsule and rotator cuff tendons are cut circumferentially around the joint while avoiding the tumor. Care is taken to protect the axillary nerve adjacent to the inferior capsule. The shoulder is dislocated, and the proximal end of the humerus is delivered into the wound. The last step of the dissection includes removing as much soft tissue and bone as is necessary to ensure a wide margin. This margin is confirmed with a frozen-section analysis of curettings from the distal medullary canal.
If the tumor involves the glenohumeral joint without involvement of the scapular body, an extra-articular resection of the glenoid is performed. The rotator cuff muscles are dissected away from their scapular origins. The capsule is kept intact, and the glenoid is osteotomized medial to the capsular attachments, retaining as much of the glenoid neck as possible.
Once the surgical margins are deemed to be negative, reconstructive procedures commence. The fresh-frozen osteoarticular allograft is thawed in the operating room immediately before use (Fig. 1). The articular surface of the allograft is cut off at the anatomic neck. The allograft capsule and rotator cuff are incised as needed to evert them and maximize lateral exposure during rasping and reaming (Fig. 2). The medullary canal is reamed to accommodate either a standard cemented or custom press-fit long-stem shoulder prosthesis. We use, and depict here, a custom Bio-Modular device (Biomet, Warsaw, Indiana) (Fig. 3). The lateral capsule and supraspinatus should be protected during preparation of the canal (Fig. 4). The host humerus is reamed separately and the osteotomy cuts are adjusted (Fig. 5). The provisionally assembled allograft-host construct is reamed to align the medullary canals of the allograft and the host humerus. The allograft should be slightly overreamed to allow it to toggle and the osteotomy to self-align when the long-stem device is implanted.
The prosthesis is then cemented into the allograft. To prevent the cement from getting onto the porous surface of the stem during this process, a latex-rubber digit, cut from a surgical glove, can be placed as a sheath over the porous surface of the stem and tied (Fig. 6). The stem can then be passed through the cement, after which the latex-rubber covering can be cut off. This composite is then inserted, with or without cement, into the distal host bone at 35° to 40° of retroversion with respect to the forearm (25° to 35° of humeral retroversion) (Fig. 7). A slight amount of over-retroversion is used to enhance anterior coverage and reduce the risk of anterior instability. Cement is not used in the distal host bone when the prosthetic stem can achieve press-fit fixation. To provide anti-rotational control to the construct, options for supplemental fixation include (1) a compression plate; (2) interlocking screws; and (3) tension-band wiring.
The soft-tissue reconstruction consists of repair of the host capsule to that of the allograft with use of interrupted, nonabsorbable sutures (Figs. 8 and 9). The humeral head should be downsized as much as necessary to avoid placing excessive tension on the rotator cuff and capsular tissue after repair. The allograft capsule is secured to the glenoid neck with suture anchors to strengthen the capsular layer. The host rotator cuff tendons are repaired to those in the allograft in a vest-over-pants fashion. The host tendons should be placed consistently, either deep or superficial to the allograft tendons. The available host tendons, including the remaining deltoid, are then repaired to allograft tendons with nonabsorbable sutures (Fig. 10). The pectoralis major tendon should not be repaired, as it seems to contribute to the development of an adduction contracture. When available, the intra-articular tendon of the long head of the biceps is used to reinforce the repair of the rotator interval between the supraspinatus and subscapularis. The coracoid or conjoint tendon is reattached to the anterior-superior edge of the glenoid or subscapularis. This is analogous to a Bristow-Latarjet repair for recurrent anterior dislocation of the shoulder4.
A pedicled rotational flap or free-flap reconstruction should be performed if there is no deltoid or fascial coverage over the allograft-prosthesis composite. The wound is closed over a suction drain. Intravenous antibiotics are given for forty-eight hours or until the drains are removed, followed by oral cephalosporin for three months. The shoulder is immobilized in a foam abduction splint in 20° to 30° of abduction and 20° to 30° of flexion to reduce tension on the surgical wound, the repaired rotator cuff tendons, and any remaining deltoid. Alternatively, the arm can be placed in a sling and swathe to prevent inadvertent external rotation or extension of the glenohumeral joint. The patient is instructed to begin passive motion after three weeks, limiting external rotation to neutral. Active motion starts after six weeks, with external rotation permitted to as much as 15°. Strengthening exercises commence after three months. The patient is then followed indefinitely at appropriate oncologic and reconstructive intervals. Radiographs are examined for evidence of glenohumeral subluxation or dislocation, host-allograft nonunion, osteolysis, fracture, and possible disease recurrence (Fig. 11).
The primary indication for this limb-salvage technique is the reconstruction of the proximal part of the humerus and glenohumeral joint following intra-articular resection of malignant or benign aggressive tumors of the proximal part of the humerus. The technique can be applied after extra-articular resections if a large glenoid neck is preserved. The technique is of particular benefit when tumor resection results in a deficiency of the soft-tissue stabilizers of the shoulder, including the rotator cuff tendons, capsule, and deltoid. Other indications for this surgical technique include the revision of a failed proximal humeral reconstruction, such as in the case of a failed endoprosthesis, allograft reconstruction, or arthrodesis.
Contraindications to this surgical technique include tumors in which the entire scapula is resected en bloc with the proximal part of the humerus. Additional absolute contraindications include active infection, the treatment of benign nonaggressive tumors for which intralesional excision is possible, and the treatment of malignant tumors in which extensive infiltration of the bone, soft tissues, and neurovascular bundle precludes limb salvage.
Mismatch of the host-allograft outer diameter. This reduces the contact area for bone apposition and healing. If the allograft is too large, and there is sufficient graft length, then an additional step-cut ledge along one-half of the allograft circumference can be used to overlap the host bone and increase stability and the appositional surface area5.
Mismatch of the host-allograft inner diameter. The prosthetic stem size may not fit into the host bone, in which case a custom prosthesis may be required. Alternatively, if the medullary canal of the allograft is smaller than the diameter of the implant, the graft may need to be reamed excessively to accommodate the stem.
Insufficient capsule or rotator cuff on the host, the allograft, or both. (A) Host: Insufficient remnant soft tissue on the host limits the potential for any active motion generated from the cuff remnant. (B) Allograft: Bringing the viable host tissue close to the allograft bone may contribute to rapid revascularization, resulting in bone resorption and fracture of the allograft. (C) Both: Despite labeling by the processor that the grafts contain soft tissue, they may not have sufficient tissue to effect a repair. An alternative material may be required to substitute for the capsule-cuff complex. Alternatives include synthetics or allograft skin (Alloderm; LifeCell, Branchburg, New Jersey) to reconstitute a soft-tissue constraint.
Damage to the capsule or rotator cuff during reaming of the allograft. The lateral tissue is vulnerable because reaming requires lateralization of the stem in the canal. Sometimes, a vertical incision of the medial capsule enables the lateral capsule to be everted and kept out of harm's way. This is preferable to cutting the lateral capsule and/or cuff since the lateral tissue is more important and difficult to reconstruct.
Humeral head size. A large head size enhances inherent stability, but it occupies space, “overstuffs” the joint, and makes the soft tissue relatively short to repair. A small size allows better soft-tissue repair but reduces the neck offset and may decrease the potential for restoration of muscle strength.
Asymmetric gapping or malaligned cuts at the osteosynthesis site. This will likely result in nonunion at the host-allograft junction.
Malalignment of the implant in the allograft during cementing, so that the canal axes do not line up. This angulates the osteosynthesis site even when the cuts are good and the apposition is excellent during trial reduction. This problem can be minimized by inserting the distal stem into the host before the cement in the proximal allograft segment has polymerized. This allows slight shifting of the implant within the allograft before the cement hardens.
Cement in the interface. The surgeon should use a scalpel and a tiny curet to clean out any cement that is pushed into the interface during insertion or that extrudes during expansion of hardening cement.
Cement in the porous surface of stems that are intended for uncemented insertion. This can be prevented by placing and then tying over the porous surface a latex-rubber digit that has been cut from a surgical glove. The stem can then be passed through the cement, after which the latex-rubber sheath can be cut off.
Postoperative positioning. Many contend that use of a so-called Statue-of-Liberty splint or spica cast helps the patient to attain more active function postoperatively.
Premature or aggressive physical therapy can tear even the best repair. Passive external rotation is particularly dangerous, causing a moment of torque at the allograft-host interface and contributing to nonunion.
The technique has been modified to make use of the Bristow-Latarjet method4 to augment anterior constraint to the joint. The inferior and posterior capsule and rotator cuff now are repaired more loosely to reduce pressure on the anterior and superior tissue reconstruction.
Investigation performed at the Orthopaedic Surgery Service, Department of Surgery, Memorial Sloan-Kettering Cancer Center, New York, NY
The original scientific article in which the surgical technique was presented was published in JBJS Vol. 91-A, pp. 2406-15, October 2009
The line drawings in this article are the work of Joanne Haderer Müller of Haderer & Müller ().
DISCLOSURE: In support of their research for or preparation of this work, one or more of the authors received, in any one year, outside funding or grants in excess of $10,000 from Biomet. In addition, one or more of the authors or a member of his or her immediate family received, in any one year, payments or other benefits in excess of $10,000 or a commitment or agreement to provide such benefits from a commercial entity (Biomet).
- Copyright © 2010 by The Journal of Bone and Joint Surgery, Incorporated