overview of endoprosthetic reconstruction -

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BACKGROUND■ Limb salvage—reconstruction following resection of malig-nant tumors of the extremities— has seen dramatic advancesin a relatively brief period of time. The traditional surgical ap-proach to the treatment of sarcoma, namely immediate ampu-tation of the extremity, was advocated in the early 1960s and1970s to ensure local control of disease.■ Early pioneers in orthopaedic oncology worked diligently todefine the optimal level of amputation and developed tech-niques to manage wounds of the pelvis and shoulder girdle fol-lowing hind- or forequarter amputation. However, such ag-gressive surgical management failed to impact overall patientsurvival, with most patients dying of metastatic disease.■ Only after the introduction of effective doxorubicin- andmethotrexate-based chemotherapy protocols in the early 1970scould alternatives to amputation be considered. A handful ofsurgeons began to challenge the orthodoxy of amputation inchildren and adults with bone sarcomas. Marcove, Francis, andEnneking were among the pioneers who developed the ratio-nale and basic techniques used in limb-sparing surgery. Theformer two surgeons were the first in the United States to de-velop endoprosthetic replacements for tumor patients.■ Starting with a very few highly selected patients with ex-tremity osteosarcoma, limb-sparing surgery now is a treatmentoption for most bone and soft tissue sarcomas, not only of theextremities, but of the pelvis and shoulder girdles as well.■ Today, over 90% to 95% of tumor patients may be ex-pected to undergo successful limb-sparing procedures whentreated at a major center specializing in musculoskeletal oncol-ogy. This dramatic alteration in patient care required signifi-cant advances along many fronts, including the following:

■ Better understanding of tumor growth and metastasis■ Determination of appropriate surgical margins■ Use of effective induction (neoadjuvant or preoperative)chemotherapy■ Development of improved approaches, preserving soft tis-sue vascularity■ Deeper understanding of skeletal biomechanics■ Advanced material engineering and manufacturingtechniques■ Development of inherently stable modular prostheses.

■ The chapters in this section outline in specific detail many ofthe surgical approaches and techniques of oncologic resectionand reconstruction currently used by leaders in the field of or-thopaedic oncology. The importance of meticulous surgicaltechnique cannot be overstated, because this is vital to ensurean optimal oncologic and functional outcome for the patient.A successful limb-sparing surgery consists of three interdepen-dent stages performed in sequence:1. Tumor resection with appropriate oncologic margins2. Reconstruction and stabilization of the involved bone andjoints

3. Restoration of the soft tissue envelope for prosthetic cover-age and function.

History of Endoprosthetic Reconstruction■ Austin Moore and Harold Bohlman, in 1940, were the firstto publish an example of endoprosthetic reconstruction for abone tumor, consisting of a custom-designed Vitallium proxi-mal femur used for a patient with a giant cell tumor of bone.■ In the early 1970s, Francis and Marcove ushered in the cur-rent age of endoprosthetic reconstruction by developing pros-theses to replace the distal femur and the entire femur for re-construction following radical resection of osteosarcomas8

(FIG 1).■ A major drawback for these custom implants quickly be-came evident: each implant would take 6 to 12 weeks to man-ufacture, during which time the patient’s tumor could progresssignificantly. This led to the development of the concept of in-duction (initially called preoperative or neoadjuvant)chemotherapy, in which the newly proven drugs doxorubicinand methotrexate were administered during the interval be-tween diagnosis and delivery of the manufactured custom im-plant.9 Both of these drugs had just been shown to have activ-ity against bone sarcomas. Induction chemotherapy has sincebeen adopted in the management of an increasingly large vari-ety of other cancers.■ As the demand for endoprosthetic reconstruction grew, awide variety of custom implants became available from a num-ber of orthopaedic manufacturers. Many of these early im-plants, however, suffered from design flaws and errors in man-ufacturing, resulting in significant problems with implant fail-ures (FIG 2A).■ However, improved material and manufacturing techniquesdeveloped for the profitable and ever-expanding market fortotal joint replacements eventually were applied to these“mega” prostheses. The adoption of the rotating hinge for im-plants around the knee and bipolar heads for the hip followedsuccessful use of these designs for total joint replacement.While these advances significantly improved the performanceof custom implants, problems with the time required for man-ufacturing and the lack of flexibility at the time of implanta-tion hampered the widespread acceptance of custom endo-prosthetic reconstruction.■ Manufacturers responded to this problem by incorporatingthe concept of modularity, adapting concepts and designs frommodular total hip and knee prostheses to develop interchange-able and easily assembled endoprosthetic systems (FIG 2B,C).Although modularity increased the complexity of the mechan-ical construct and carried a risk of failure associated with thesum of all of the components, these potential problems wereeasily outweighed by significant benefits.

■ The primary advantage of a modular endoprosthesis is thesystem’s flexibility: the surgeon can concentrate on perform-ing the best possible oncologic resection knowing that any

Chapter 3Martin M. Malawer, Robert M. Henshaw, and Kristen Kellar-Graney

Overview of EndoprostheticReconstruction

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2 Part 4 ONCOLOGY • Section I SURGICAL MANAGEMENT

changes in the preoperative plan can be accommodated byselecting those components that fit the patient’s anatomyand actual skeletal defect optimally.■ Modular trial components allow the surgeon to mix andmatch pieces and test the reconstruction prior to selectionand assembly of the actual final prosthesis.■ Standardization of components permits the implant man-ufacturer to increase the level of quality control greatly,while reducing the overall cost of manufacturing througheconomies of scale.■ Modular systems reduce overall inventory and time to de-livery while providing a large choice of prosthetic shapesand sizes.■ Modular systems permit hospitals to maintain an on-siteinventory that has allowed these systems to be available im-mediately as a backup option for selected non-oncologic pa-tients, such as those undergoing difficult joint revisionsurgery or patients with significant periarticular fractures.

■ A first-generation modular endoprosthetic system was theHowmedica Modular Replacement System (HMRS,Howmedica International, Limerick, Ireland), designed andmanufactured in Europe. This system featured intramedullarycementless press-fit stems supported by external flanges and

cortical transfixation screws, while the knee mechanism con-sisted of a simple hinge design. Although the system truly wasmodular, in clinical practice the long-term outcomes were dis-appointing. Significant problems encountered with this deviceincluded aseptic stem loosening (osteolysis), substantial stressshielding with bone resorption, screw fracture and migration,and a polyethylene failure rate higher than 40% for the kneemechanism.4,6 Consequently, this system rarely was used inthe United States.■ An example of a second-generation modular system is thesaddle endoprosthesis (Waldemar-Link, Germany; FIG 3A,B).This prosthesis, originally designed for the treatment of in-fected failed total hip replacements, was modified to allow forreconstruction of the hip following resection of the pelvis.■ The unique feature of this system is the saddle itself, whichis a U-shaped component that straddles the ilium, allowingmotion in flexion–extension, and abduction–adduction in theanteroposterior and lateral planes against the bone.■ The saddle is attached with a rotating polyethylene linedring, increasing the degree of freedom and allowing for hip ro-tation. These are attached to a series of interchangeable mod-ular bodies that, in turn, connect to a standard cementedfemoral stem.

FIG 1 • The first known distal femoral replacement wasperformed in the United States, by Kenneth Francis, at NewYork University in 1973. A. Distal femoral osteosarcomatreated with doxorubicin prior to surgical resection.B. Cemented distal femoral replacement with longintramedullary stems. This prosthesis used a modifiedWalldius fixed knee hinge. C. Scan of the front page of anhistoric JBJS article. Original publication of the first prosthe-sis performed in the United States. D. Original prosthesisimplanted by Drs. Bohlman and Moore for fibrous dysplasiaof the proximal femur. E. Custom segmental prosthesis usedduring 1980s prior to the development of the ModularReplacement System by Howmedica, Inc. (Rutherford, NJ).(A,B: Courtesy of Martin M. Malawer; C: reprinted fromJBJS, 1940, with permission.)

A B C

D E

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Chapter 3 OVERVIEW OF ENDOPROSTHETIC RECONSTRUCTION 3

FIG 2 • A. Examples of failed, retrieved, custom endo-prosthetic implants used during the 1980s. The mostcommon mode of mechanical failure was stem break-age or bending, typically due to small stem diameteror from stress risers caused by the sharp transitionfrom the prosthetic body to the stem. B. Modular im-plant design featuring a Kinematic rotating-hingeknee. Interchangeable components permit easy off-the-shelf flexibility in the operating room, allowingthe implant to match the patient’s anatomy. C. Intraoperative assembly of the prosthesis requiresimpaction of locking Morse tapers to connect thestem, body segments, and joint modules. (Courtesy ofMartin M. Malawer.)

A

C

B

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A

B

C-E

FIG 3 • Modular saddle prosthesis (Waldemar-Link, Hamburg Germany) for reconstruction of ac-etabular defects. A. Originally designed for revision total hip surgery, modular components of in-creasing size permit reconstruction of the pelvis after periacetabular resection. The prosthesis con-sists of the saddle portion, which articulates with the ilium (1); the base element, which provideslateral offset and allows for rotation (2,3); and the femoral stem (4). B. Postoperative radiograph9 months after partial pelvic resection demonstrating preservation of leg length. C. Custom distalfemoral replacement used in 1982. D. Custom prosthesis (1984–1988) now incorporating a porouscollar to permit extracortical bone fixation. E. Modular distal femoral replacement introduced in1988, featuring interchangeable off-the-shelf components. This system, with minor modifications,is still in use today. (A,B: Courtesy of Martin M. Malawer.)

■ This device preserves limb length following resection of theperiacetabulum (eg, type 2 pelvic resection, modified internalhemipelvectomy) while functioning like a total hip prosthesis.The clinical and functional results following saddle reconstruc-tion of the pelvis with this system have been promising.1■ The first successful universal modular system was intro-duced in 1988 as the Modular Segmental Replacement System(MSRS, Howmedica Inc, Rutherford, NJ), renamed theModular Replacement System (MRS) and now available as theupdated Global Modular Replacement System (GMRS;Stryker/Howmedica Inc., Mahwah, NJ; FIG 3C–E).

■ This system was designed to provide modular replace-ments for the proximal humerus, proximal femur, totalfemur, distal femur, and proximal tibia and has been instru-mental in the widespread adoption of endoprosthetic recon-struction following segmental bone resection.

■ The growing popularity of endoprosthetic reconstructionhas led to the introduction of similar modular systems fromseveral orthopaedic manufacturers (eg, Orthopaedic SalvageSystem [Biomet, Warsaw, IN], Guardian Limb Salvage System[Wright Medical Technology [Arlington, TN]).■ Current implant manufacturers still offer customized solu-tions for challenging anatomic issues. However, these customimplants often consist of a custom module mated to an exist-ing modular system to ensure maximal flexibility.

TYPES OF ENDOPROSTHETICRECONSTRUCTION■ Specific anatomic examples of endoprosthetic reconstruc-tion are discussed in the following paragraphs.

Hip■ Tumors involving the proximal femur are extremely com-mon, and include both primary sarcomas and metastatic

carcinomas. Replacement of the proximal femur (FIG 4) isreadily accomplished following resection of a primary tumoror fracture through a subtrochanteric metastatic lesion. Abipolar hemiarthroplasty is used for the hip joint, with softtissue reconstruction of the hip capsule to minimize the risk ofdislocation.2 Reconstruction of the hip abductors is accom-plished directly via laterally placed holes or loops, or, if a por-tion of the trochanter was saved, by use of a trochanteric clawwith cerclage cables. Less common are resections of the entirehip joint (ie, type II pelvic resection and its modifications).This defect can be reconstructed with a saddle prosthesis orwith the recently designed partial pelvic implants that attachto the remaining ilium. Stability is achieved by balancing themuscle tension between the medial iliopsoas and the lateralhip abductors.

Distal Femur■ The distal femur is the single most common site for primarybone sarcomas. Endoprosthetic reconstruction (FIG 5) requiresa unique combination of flexibility combined with overall sta-bility, because the knee capsule and the cruciate and collateralligaments are removed during the resection. The Kinematic ro-tating hinge knee (GMRS, Stryker/Howmedica, Mahwah, NJ)and similar partially constrained hinged designs permit sub-stantial flexion–extension as well as rotation at the anatomicaxis of the knee, while providing inherent stability in thevarus–valgus and anterior–posterior planes. Reconstruction ofthe extensor mechanism rarely is necessary, because the patellaoften can be saved during the resection. Resurfacing of thepatella is possible, but often unnecessary.

Total Femur■ Patients presenting with extensive intramedullary tumors(eg, Ewing sarcoma or the rare diaphyseal osteosarcoma), as

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well as patients with multiply failed total joints and little re-maining bone stock, can be treated with a total femoral re-placement (FIG 6). Modular systems provide a readily avail-able solution by combining distal femoral and proximalfemoral components by means of interbody segments. Thistype of reconstruction has proven to be extremely durable be-cause of the combination of the high degree of freedom asso-ciated with the two separate but related joints.

Proximal Tibia■ The tibia is anatomically unique in its anterior subcuta-neous border and patellar tendon insertion. Routine use of agastrocnemius rotation flap has dramatically reduced the in-cidence of postoperative complications, and compound re-construction of the tendon insertion and careful attention topostoperative rehabilitation can result in minimal extensorlag. Joint stability at the knee is ensured by using the same

rotating hinge design used for distal femoral replacements(FIG 7). Meticulous soft tissue reconstruction of the extensormechanism is crucial for the postoperative function of thisprosthesis.

Proximal Humerus■ High-grade sarcomas of the proximal humerus requireextra-articular resection, including the entire rotator cuff anddeltoid muscles, to minimize the risk of local recurrence (FIG8). Accordingly, ultimate functional outcome may be greatlyrestricted. A combination of static and dynamic suspension,including transfer of the pectoralis muscle, stabilizes the prox-imal humerus to the scapula, permitting painless and func-tional use of the elbow, wrist, and hand. Low-grade tumorscan be treated with intra-articular resections; preservation ofthe rotator cuff and deltoid can lead to function comparable tothat provided by total shoulder replacements.


FIG 4 • Proximal femoral replacement. A. MRS proxi-mal femoral replacement featuring porous coatingand a lateral loop to facilitate reconstruction of thehip abductors. B. Postoperative radiograph demon-strating proximal femoral replacement followingtumor resection. Note that bipolar arthroplasty of thehip is performed routinely to improve hip stability,and trochanteric reconstruction using a claw with ca-bles is used to restore hip abduction. C. Periacetabularand proximal femoral replacement using aHowmedica customized pelvic replacement for os-teosarcoma of the femoral head involving the hipjoint. D. Intraoperative view showing cemented fixa-tion of pelvic implant to iliac wing. E. Postoperativeradiograph demonstrating restoration of leg lengthand lateralization of hip. (A,B: Courtesy of Martin M.Malawer.)

A B C

D E

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FIG 5 • Distal femoral replacement. A,B. Kinematic rotating hinge mecha-nism featuring an all-polyethylene tibial component permits a full rangeof flexion, rotation, and axial motion while restraining the knee in the APand medial–lateral planes, respectively. C. Intraoperative view of distalfemoral replacement after final assembly of the components. D–E. Distalfemoral and proximal tibia modular replacement system. This system per-mits reconstruction of several segments of various bones simultaneously ifrequired. (A,B: Courtesy of Martin M. Malawer.)

A B

C

D

E

FIG 6 • Total femoral replacement for osteosarcoma of the femur.A. Implant and trial components consist of a modular proximalfemoral replacement connected to a modular distal femoralreplacement of means of a male-to-male interbody segment.B. Postoperative radiograph demonstrating bipolar hip and rotatinghinge joints.A B

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Scapula■ Following scapulectomy, endoprosthetic replacement of thescapula and glenohumeral joint lateralizes the humerus andimproves stability and function of the shoulder (FIG 9). Newscapular designs feature a locking articulation to improve sta-bility, while use of a large-diameter Gore-Tex (W. L. GoreLtd., Flagstaff, AZ) vascular graft to restore a joint capsulehelps to ensure optimal stability. As with proximal humeral re-placement, ultimate functional outcome depends on theamount of muscle that can be preserved during the resection.Multiple muscle transfers are necessary to stabilize and powerthe prosthesis as well as to provide adequate coverage.

Elbow■ The elbow joint is not often affected by sarcomas ormetastatic disease. Customized, hinged implants with small-

caliber stems to fit the ulna can be used provided sufficient softtissue remains to cover the prosthesis. Function depends onpreservation of the biceps insertion.

Total Humerus■ As with the total femur, the total humerus implant is a com-bination of a proximal humeral implant and an elbow replace-ment. Indications for this procedure are rare, but preservationof a sensate, functional hand remains superior to any amputa-tion prosthesis.

Calcaneus■ One case has been reported of a total calcaneal prosthesisimplanted for osteosarcoma in lieu of a below-knee amputa-tion. Ten years after surgery, the patient remained fully ambu-latory without assistive devices.

FIG 7 • Proximal tibial replacement for fibrosar-coma of bone. A. Assembled prosthesis, featur-ing a Kinematic rotating hinged knee and aresurfacing component of the distal femur. B.Intraoperative view showing final implant, withgastrocnemius flap being rotated for coverage ofthe implant and reinforcement of the patellartendon reconstruction. C. Intraoperative photo-graph of a proximal tibia MRS replacement. D.Soft tissue reconstruction and reestablishment ofthe extensor mechanism. Medial gastrocnemiustransfer to cover the prosthesis is an essentialstep in the reconstruction portion of the surgery.A

B D

C

FIG 8 • Proximal humeral replacement. A. Trial and actual implants compared to resection specimen. B. Intraoperative view demonstrating use of multiple woven Dacron tapes for reattachment of the rotatorcuff tendons.

A B

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Intercalary Endoprostheses■ Replacement of the central portion of a long bone followingdiaphyseal resection for tumor has the significant advantage ofpreserving the patient’s native adjacent joints in the humerus,femur, and tibia. Traditional implants limited the indicationfor this type of reconstruction due to the amount of remainingbone required to fix the prosthetic stems securely. Customizedstems using crosspin fixation and the newer Compress fixationmethod (Biomet) have greatly expanded the indications forthis procedure (FIG 10).

Expandable Implants for Skeletally Immature Patients■ Reconstruction of the axial skeleton in immature patientsremains challenging (FIG 11). Children over 10 to 12 years ofage often can be treated similarly to adults, using smaller ver-sions of the modular prostheses, occasionally in combinationwith contralateral epiphysealdesis to equalize leg lengths atskeletal maturity. For children younger than 5 years, primaryamputation remains the preferred solution, given the difficultyin obtaining a proper oncologic margin around the criticalneurovascular bundles. Between these two age groups, recon-struction is feasible, but limb-length inequality becomes func-tionally disabling as the child grows. Use of implants that canbe expanded multiple times during growth permits prosthetic

reconstruction for these children. These custom-created im-plants have been used in both the upper and lower extremitywith mixed results, as mechanical failures of the expansionmechanism is not uncommon. Whereas traditional expandableimplants would require multiple invasive procedures toachieve expansion (with some patients undergoing 10 or moresurgeries), the recently introduced custom Rephyisis noninva-sive expandable implant (Wright Medical Technology,Arlington, TN) features a unique method of expansion thatdoes not require surgery.

PATIENT SELECTION FORENDOPROSTHETIC RECONSTRUCTION■ Appropriate patient selection for limb-sparing surgery is es-sential to ensure optimal outcomes. While the introduction ofeffective chemotherapy for osteosarcoma was a major impetusin the development of limb-sparing techniques, increasing pa-tient survival has placed greater emphasis on functional out-come and durability of reconstruction. Patients expect solu-tions that address their functional, cosmetic, and psychologicalneeds and demands, and often reject the option of amputation.■ Although tumor size and location often are the determiningfactors in selecting patients for limb salvage, neoadjuvant (pre-operative) chemotherapy may convert formerly unsalvageable


FIG 9 • Total scapular replacement. A. Modular system composed of light-weight scapular body with locking mechanismthat captures a proximal humeral implant. B. Intraoperative view of total scapular replacement demonstrating use of Gore-Tex graft for reconstruction of capsule around the interlocked joint. C. Postoperative radiograph of total scapularreplacement. The prosthesis lateralizes the arm, helping to improve stability and function following resection. D. Newestversion (third-generation) of a “snap fit” Scapula prosthesis, which is mated to an MRS proximal humeral prosthesis. The useof a scapula prosthesis is functionally superior to the older technique of a “hanging” shoulder. E. Intraoperative reconstruc-tion to stabilize a scapula prosthesis. The latissimus, rhomboids, deltoid, and trapezius muscles are required. Most shoulder-girdle, axillary, and scapula tumors can be treated by a scapular prosthesis if the scapula is involved. (C: Courtesy of Martin M.Malawer; E: From Pritsch T, Bickels J, Wu CC, et al. Is scapular endoprosthesis functionally superior to humeral suspension?Clin Orthop Relat Res 2007;456:188–95.)

C D E

A B

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patients to candidates for limb-sparing procedures by inducingsignificant tumor response. Consequently, a complete reevalu-ation of the patient following neoadjuvant treatment is neces-sary before an appropriate surgical plan is selected. For appro-priate patients, endoprosthetic reconstruction offers a durableand functional option for skeletal reconstruction.■ Limb-sparing procedures should not be limited to patientswith favorable response to treatment. Patients with poor prog-nostic factors, such as metastatic disease at time of initial pre-sentation or tumor growth during chemotherapy, often require

surgery for local control of disease and palliation of symptomssuch as pain. Although amputation may be necessary forsome, limb-sparing surgery can avoid the significant psycho-logical impact associated with mutilative procedures.Endoprosthetic reconstruction offers immediate stability andrapid mobilization while avoiding the need for prolongedbracing, crutches, or inpatient rehabilitation.■ The proven success and durability of endoprosthetic recon-struction has led to its adoption for other challenging, nontu-morous conditions in which restoration of a segmental skele-


A CB

FIG 11 • Repiphysis expandable endoprosthetic replacement (Wright Medical, TN). A. Distal femoral replacement for os-teosarcoma in a skeletally immature child. B. Expansion of implant is accomplished using an external radiofrequency coilplaced around the implant. Induced heating of the prosthesis melts the inner plastic, allowing the compressed spring toexpand; removal of the RF field allows the plastic to harden, locking the implant into place. C,D. Fluoroscopic views ofthe implant during expansion demonstrating a 1-cm lengthening.

A

B DC

FIG 10 • Intercalary replacement of the distal tibia forosteosarcoma using a customized Compress (Biomet)prosthesis. A. Preoperative radiograph.B. Intraoperative view showing the implant; musclecoverage was obtained using the tibialis anterior.C. Postoperative view showing position of implant.The short distal intramedullary stem is augmentedwith bone cement for secure fixation.

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tal defect is required.7 For example, patients with multiplefailed total joint replacements around the hip and knee maydevelop significant bone loss that cannot be corrected readilywith traditional revision total joint components. In this subsetof patients, resection of the failed prosthetic joint and removalof all devascularized bone followed by reconstruction with a“tumor” endoprosthesis can lead to significant functional re-covery.■ Similarly, severely comminuted periarticular fractures notamenable to internal fixation can be addressed by removal ofthe fragmented bone and replacement with a segmental endo-prosthesis. This procedure is extremely valuable for the obese,elderly patient with osteoporotic bone (often with significantmedical comorbidities) who trips and falls on the knee, result-ing in a type C distal femur (or, if a total knee replacement isin place, periprosthetic) fracture. Endoprosthetic reconstruc-tion can be performed in a fraction of the time necessary formeticulous internal fixation, and since the prosthesis is inher-ently stable, the patient can begin immediate weight bearingwithout functional bracing.

GUIDELINES FOR ENDOPROSTHETICRECONSTRUCTION■ Regardless of the anatomic location, certain basic principlesapply to all endoprosthetic reconstructions. Restoration of thenormal axis of motion and extremity length depends on com-ponent selection. Careful attention to implant size and soft tis-sue reconstruction also can optimize functional outcomes.Proper stem selection, bone preparation, cementation tech-nique, and use of extracortical fixation can reduce the risk ofaseptic loosening and maximize implant longevity.■ Following resection of a bone tumor, careful measurementof the specimen is necessary to select the desired implantlength. Trial components, available with all modular systems,permit easy comparison with the specimen and permit multi-ple trial reductions to determine optimal length and position-ing for the final implant.■ Meticulous preparation of the intramedullary canal is donefor stem insertion. Selection of the stem diameter depends onthe anatomy of the canal, which should be sequentially reamedso that it can accommodate the largest diameter stem possible.■ Tendon and soft tissue reconstruction is determined by theanatomic site and the amount of residual tissue followingtumor resection. Again, functional outcome can be enhancedwith meticulous attention to details and restoration of properbiomechanics.■ Rotational muscle flaps often are necessary to ensure ade-quate soft tissue coverage and also may serve to reinforce ten-don attachments or capsular tissue.■ Frequently performed transfers include the following:

■ Shoulder. Transfer of the pectoralis major and latissimusdorsi muscles covers and dynamically stabilizes a proximalhumeral prosthesis. Dacron tapes are used to suspend theprosthesis statically from the scapula.■ Hip. Transfer of the psoas and external rotators is per-formed to create a pseudocapsule around the prosthetichead. This capsule then is reinforced with circumferentialDacron tapes to prevent dislocation. Reattachment of theabductor muscles is necessary to minimize theTrendelenburg lurch in the postoperative phase. This limpimproves over time with strengthening of the abductors.

■ Knee. Twenty-five percent of distal femoral replacementsand all proximal tibial replacements require rotation of agastrocnemius muscle (typically the medial head) to repairthe soft tissue defect following resection of a tumor aroundthe knee. In addition, this local flap is incorporated into thereconstruction of the patellar tendon for proximal tibialreplacements.7

■ Final closure of the wound may be jeopardized by skin lossfollowing resection of a biopsy tract. In general, patients withvery large tumors often have redundant skin because thetumor has acted as an internal skin stretcher. This extra skinmay be rotated or trimmed as needed to facilitate wound clo-sure. Excess skin along the incision should be excised to avoidmarginal wound necrosis related to disruption of the mi-crovasculature from elevation of large subcutaneous flaps.Patients with tight skin closures are best served by leaving theskin open to avoid pressure-induced ischemia, and performinga primary or secondary split-thickness skin graft.■ Limbs should be elevated maximally in the postoperativephase to reduce swelling that can jeopardize the wound closure.■ Use of large-bore closed suction drains and correction ofany postoperative coagulopathies help prevent hematoma for-mation. Patients who develop hematomas or wound break-downs require aggressive treatment in the operating room toprevent secondary infection of the endoprosthesis.

CLINICAL RESULTS FOLLOWINGENDOPROSTHETIC REPLACEMENT■ Prosthetic survival has improved dramatically as improvedsurgical techniques, advanced prosthetic designs, and modernmanufacturing techniques have been adopted. Results of earlycustom prostheses were disappointing, leading many surgeonsto use allografts or other methods of reconstruction.■ More recently, there has been increased interest in endo-prosthetic reconstruction as multiple centers have reported im-proved outcomes. Informal polling of members of theMusculoskeletal Tumor Society has shown a significant swingfrom a majority of members using primarily allograft recon-structions to a majority of members using endoprostheticreconstruction.■ Recently published results looking at long-term survival of242 cemented endoprosthetic replacements9 demonstrated anoverall survival of 88% at 5 years and 85% at 10 years(Table 1). Prosthetic survival varied by type and location,with the poorest survival seen in patients with early custom-designed implants and in patients with proximal tibial re-placements. Infection was the single most common cause ofimplant failure, with infected patients having an 83% risk ofimplant failure (FIG 12).■ Functional results vary by implant location. Outcomes fol-lowing reconstruction of the distal femur in 110 patients werejudged as good to excellent in 85% of patients.3

COMPLICATIONS■ Complications following any type of limb-sparing recon-struction are not uncommon. Most patients have depressedimmune systems from chronic disease, chemotherapy, andmalnutrition. Patients often are anemic and have clotting ab-normalities, including thrombocytopenia. The presence oflong-term indwelling catheters for the administration of


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chemotherapy may lead to unrecognized bacteremia and po-tential hematogenous seeding of the operative site.■ The anatomic location of a tumor and necessary resectionmay result in significant disruption of the venous and lym-phatic drainage of the extremity during resection, leading tovenous stasis, swelling, and lymphedema. This can leadquickly to flap necrosis during the postoperative period, sec-ondary infection, and eventual amputation.■ Finally, oncologic complications, including local recurrenceof tumor or tissue necrosis from radiation, may result in fail-ure of a limb-sparing procedure.■ Complications specific to endoprosthetic reconstructionmay be related to mechanical or biologic factors. Prostheticfracture, disassociation of modular components, fatigue fail-ure, and polyethylene wear have been described. Improved im-plant designs, metallurgy, and manufacturing techniques canreduce the incidence of these problems significantly.■ Our institutional experience with more than 200 MRS(Materials Research Society, Warrendale, PA) implants overthe past 18 years have revealed no stem fractures, body frac-tures, or taper disassociations to date. Polyethylene bushingfailure occurs in fewer than 5% of patients with the Kinematicrotating hinge mechanism (Howmedica, Rutherford, NJ).

■ Biologic failure of an endoprosthesis may occur as a resultof joint instability, aseptic loosening, or periprosthetic frac-ture of bone around the prosthesis. Meticulous attention tosoft tissue reconstruction has virtually eliminated joint insta-bility as a problem. The use of circumferential porous coat-ing, properly sized large-diameter stems, and third-genera-tion cementation techniques has helped to prevent asepticloosening in our patients. Surgical technique and the use ofpolished cemented stems have prevented periprosthetic frac-tures during surgery. Several patients with secondary, latefractures as a result of blunt trauma (eg, falls, auto accidents)have been treated successfully with casting and protectedweight bearing.

FUTURE TRENDS FORENDOPROSTHETIC RECONSTRUCTION■ Current modular endoprosthetic reconstruction has greatlyfacilitated limb-sparing surgery following resection of bonesarcomas. Its success also has expanded the indications to in-clude bone defects for non-oncologic problems. Increasing ex-perience in the salvage of failed total joint replacements,chronic nonunions of fractures, and reconstruction followingradical resection of osteomyelitis has shown that the proven


Prosthesis No. No. Median Survival at 5-yr survival 10-yr survivalType patients failures F/U (mos) median F/U (95% CI) (95% CI)MRS PH 36 4 30 0.89 0.89 (0.70–1.00) 0.76 (0.30–1.00)MRS PF 22 0 25 1.00 1.00 1.00MRS DF 78 11 29 0.94 0.86 (0.78–0.94) 0.76 (0.56–0.94)MRS PT 31 7 33 0.94 0.86 (0.33–1.00) 0.65All MRS 173 22 30 0.93 0.86 (0.82–0.91) 0.76 (0.64–0.88)All custom implants 50 23 85 0.71 0.81 (0.77–0.87) 0.55 (0.47–0.62)All limbs 242 55 37 0.92 0.88 (0.85–0.90) 0.85 (0.81–0.90)

Table 1 Long-term Survival of 242 Endoprosthetic Replacements From a SingleInstitution Based on Kaplan-Meier Survival Analysis*

*Failure was defined as implant removal for any reason; patients were censored at time of last follow-up or at time of death.DF, distal femur; MRS, Modular Replacement System; PF, proximal femur; PH, proximal humerus; PT, proximal tibia.

FIG 12 • A. Kaplan-Meier survival curve comparing all Modular Replacement Systems by anatomic site. Proximal femur and proximalhumerus replacements have the most superior survival results, followed by distal femur, and then proximal tibia. B. Kaplan-Meier sur-vival curve showing superior results of modular replacement system when compared to custom prostheses over all anatomic sites.

BA

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concepts of limb-sparing surgery can be applied to many dif-ferent clinical situations. Today, more endoprosthetic recon-structions are performed for non-oncologic reconstructionsthan for osteosarcomas.■ Ongoing research continually strives to improve the out-come following endoprosthetic reconstruction. Continuedwork on improved metallurgy and polymers, particularly withthe introduction of cross-linked polyethylene, promises im-proved long-term durability. Routine use of premixed antibi-otic cement and experimentation with antimicrobial implantsurfaces may help to reduce the risk of periprosthetic infection.New techniques for tendon attachment to the prosthesis in-clude novel clamps and ingrowth surfaces to promote im-proved junctional strength.■ New implant technologies such as the Rephyisis noninvasiveexpandable prosthesis offer hope to younger children with fewalternative options. New fixation methods, including hydrox-yapatite stems with porous coated surfaces, may be of greatvalue in non-oncologic patients.■ The recently introduced Compress system represents thefirst new method of prosthetic fixation in decades. We havealready adapted this system to expand the applicability of in-tercalary endoprosthetic reconstruction. Although future ad-vances in tissue engineering hold the promise of artificiallyengineered living bone, we expect that endoprosthetic recon-struction will remain the preferred choice of orthopaedistsfor many years to come.

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6. Kawai A, Muschler GF, Lane JM, et al. Prosthetic knee replacementafter resection of a malignant tumor of the distal part of the femur. JBone Joint Surg Am 1998;80A:636–647.

7. Malawer MM, Price WM. Gastrocnemius transposition flap in con-junction with limb-sparing surgery for primary bone sarcomasaround the knee. Plast Reconstr Surg 1984;73:741.

8. Marcove RC, Lewis MM, Rosen G, et al. Total femur and total kneereplacement. A preliminary report. Clin Orthop 1977;126:147–152.

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