In the literature, long-term survival of endoprosthetic reconstruction varies widely. Few long-term reports analyze both anatomical and disease-specific implant and patient survival. We retrospectively reviewed the results of 489 patients who underwent resection of musculoskeletal tumor and reconstruction using an endoprosthetic device between December 1980 and August 2009. Implants were considered to have failed if the cemented components were revised for any reason, or the major body segment was removed for any reason. Implant survival, limb survival, and patient survival were determined using the Kaplan-Meier method. Sixty-one (12.5%) of the 489 cases were revised at a mean follow-up of 6.6 years (range, 1 month to 27.3 years). Kaplan-Meier analysis revealed overall implant survival of 23.1% at 27 years (95% CI, 5.0% to 100.0%). At 15 years, modular implants outperformed older custom designs (90.8% and 59.6% survival, respectively; P < .05). Complications that led to failure of the limb-salvage effort included local recurrence (21 cases), infection (11), positive surgical margins (3), and intractable pain (1). Thirty-six amputations (7.4%) were performed. There were no cases of amputation performed as a direct outcome of mechanical failure. Endoprosthetic implants provide a reliable, durable method of reconstruction after resection of musculoskeletal tumors.

BACKGROUND:Advocates of newer implant designs cite high rates of aseptic loosening and failure as reasons to abandon traditional cemented endoprosthetic reconstruction of the distal femur.QUESTIONS/PURPOSES:We asked whether newer, modular distal femoral components had improved survivorship compared with older, custom-casted designs.PATIENTS AND METHODS:We retrospectively reviewed 254 patients who underwent distal femoral endoprosthetic reconstruction. We excluded two patients with cementless implants, 27 with expandable prostheses, and 39 who had a nontumor diagnosis. This left 186 patients: 101 with older custom implants and 85 with contemporary modular implants. The minimum followup was 1 month (mean, 96.0 months; range, 1-336 months). The tumor was classified as Stage IIA/IIB in 122 patients, Stage IA/IB or benign in 43, and Stage III or metastatic in 21.RESULTS:Kaplan-Meier analysis revealed overall 10-, 20-, and 25-year implant survival rates of 77%, 58%, and 50%, respectively, using revision of the stemmed components as an end point. The 85 modular components had a greater 15-year survivorship than the 101 custom-designed implants: 93.7% versus 51.7%, respectively. Thirty-five stemmed components (18.8%) were revised for aseptic loosening in 22 patients, implant fatigue fracture in 10, infection in two, and local recurrence in one.CONCLUSIONS:Cemented modular rotating-hinge distal femoral endoprostheses demonstrated improved survivorship compared with custom-casted implants during this three-decade experience. Patients with low-grade disease and long-term survivors of high-grade localized disease should expect at least one or more revision procedures in their lifetime.LEVEL OF EVIDENCE:Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

BACKGROUND:The few available studies documenting the long-term survival of cemented proximal tibial endoprostheses for musculoskeletal tumors do not differentiate between stem designs or patient diagnosis. There is wide variation in survival rates reported, possibly a result of this heterogeneity in patient population and implant design.QUESTIONS/PURPOSES:We therefore asked: (1) How long do proximal tibial endoprostheses last? (2) What is the typical long-term functional result after proximal tibial replacement? And (3) what are the short- and long-term complications associated with endoprosthetic reconstruction of the proximal tibia, particularly with respect to the soft tissue reconstruction?PATIENTS AND METHODS:We retrospectively reviewed 52 patients with 52 proximal tibial endoprosthetic reconstructions for a tumor-related diagnosis. Kaplan-Meier survivorship analysis was performed using revision of the stemmed components for any reason as an endpoint for implants, and death due to disease progression for patients. Function was assessed using the MSTS scoring system. The minimum followup was 1 month (mean, 96 months: range, 1-284 months; median, 69 months).RESULTS:Using revision of the stemmed components for any reason as an end point, overall prosthesis survival at 5, 10, 15, and 20 years was 94%, 86%, 66%, and 37%, respectively. The 29 modular implants demonstrated a trend toward improved survival compared to the 23 custom-designed components, with a 15-year survivorship of 88% versus 63%. The mean postoperative Musculoskeletal Tumor Society score at most recent followup was 82% of normal function (mean raw score, 24.6; range, 4-29).CONCLUSIONS:Cemented endoprosthetic reconstruction of the proximal tibia provides a reliable method of reconstruction following tumor resection.

Background As the life expectancy of patients with musculoskeletal tumors improves, long-term studies of endoprosthetic reconstructions are necessary to establish realistic expectations for the implants and compare them to other reconstruction approaches.Questions/purposes (1) What is the long-term survival of cemented bipolar proximal femoral replacements? (2) How does prosthesis survival compare to patient survival among patients with Stage I, II, and III disease? (3) Do modular implants outperform custom-built prostheses? (4) Do some proximal femoral replacements require conversion to THA?Patients and Methods We retrospectively reviewed all 86 proximal femoral replacements used for tumor reconstruction from 1982 to 2008. Primary diagnoses were 43 high-grade tumors (IIA/IIB), 20 low-grade tumors (IA/IB or benign), and 23 with metastatic disease. We reviewed prosthesis survival, patient survival, complication rates, functional outcomes, and rates of conversion to THA.Results Five of 86 patients (5.8%) required revision of the femoral component. Five-, 10- and 20-year implant survivorships were 93%, 84%, and 56%, respectively. All patients with low-grade disease survived; the 5-year survival rate for patients with metastatic disease was 16%; the 5-, 10-, and 20-year survival for IIA/IIB patients was 54%, 50%, and 44%, respectively. Five of 86 patients (5.8%) underwent conversion to THA for groin pain.Conclusions Cemented bipolar proximal femoral replacements after tumor resection proved a durable reconstruction technique. The implants outlived patients with metastatic disease and high-grade localized disease while patients with low-grade disease outlived their implants. The survival of modular prostheses was comparable to that of older, one-piece custom designs.

BACKGROUND CONTEXT:The use of minimally invasive lumbar intradiscal heating techniques, including intradiscal electro-thermal therapy (IDET), endoscopic radio-frequency annuloplasty, nucleoplasty and laser discectomy, for chronic lumbar discogenic pain and contained disc herniation has recently gained popularity. The purported therapeutic mechanisms of these interventions include subtotal nuclectomy, annular nociceptor ablation, and stabilization of the annular fibers. Basic science data elucidating the biomechanical and histomorphologic alterations of heat treatments on disc remain sparse. PURPOSE:The purpose of this study is to examine the effects of uniform heating on biomechanical properties and histomorphology of intervertebral disc tissues using a porcine model. STUDY DESIGN/SETTING:In a laboratory setting, porcine functional spinal units consisting of vertebra-nucleus pulposus-vertebra core and porcine hamstring tendons were harvested. Studies were performed on these tissue samples by uniformly heating the specimens in a constant temperature water bath. Ten porcine lumbar disc core and twenty-five porcine hamstring tendons were utilized as the subjects for this study. The effects of uniform heat treatments on disc core and hamstring tendon were measured for shrinkage, stiffness, and load to failure strength. Histomorphological study was also carried on the same specimen. METHODS:The porcine vertebra-nucleus pulposus-vertebra segments were cored to a uniform 1-cm diameter. The hamstring tendons were cut to uniform 1.2-inch lengths. The tendon specimens were divided into groups of five each and heated in constant temperature water baths of 60 degrees C, 65 degrees C, 70 degrees C, or 75 degrees C for 10 min. Unheated specimens served as controls. The disc core specimens were divided in two group of five each, and tested at room temperature or after immersion in a 70 degrees C bath. The shrinkage was monitored during immersion in the water bath. Biomechanical testing to failure was carried out using mechanical loading on an MTS servohydraulic testing machine operating under stroke control. Strength and stiffness of the tissue was determined. Histomorphology was studied by staining the specimen with hematoxylin and eosin (H&E), and examined under 200 times magnification. Non-heated controls were used for comparisons. RESULTS:The porcine hamstring tendons had no measurable shrinkage in specimens heated up to 65 degrees C. At temperatures above 65 degrees C, the shrinkage was concluded within 2 min of immersion and 70 degrees C appeared to be the optimal temperature, as temperatures higher than this did not demonstrate incremental effects. The disc core samples were heated to 70 degrees C (optimum temperature), and there appeared to be gross contraction of the disc core circumference to visual inspection, but no measurable lengthwise shrinkage could be appreciated. Histologically, the specimens demonstrated progressive loss of individual collagen fiber outline as the temperature increased. In the tendons, at 75 degrees C all of the fibers appear to be fused together, and the voids between individual collagen fibers were no longer present. Biomechanical testing revealed that the tendons undergo a substantial reduction in stiffness after heating. The mean tendon stiffness for the unheated specimens was 19,356 psi, while the corresponding value for the heated tendons was 1023 psi. These were significantly different using the paired t-test at p=0.0043. For the disc core samples, there was no significant difference in either stiffness (p=0.182) or failure strength (p=0.998) after heating. All failures occurred in mid-substance of the specimen. CONCLUSIONS:The application of uniform heating to nucleus pulposus disc core caused visible contraction of its circumference but not lengthwise shrinkage. The same heating shrinks the hamstring tendon and reduces its stiffness. Ultimate failure strength of the disc core specimen remains unchanged. The failure data was not obtainable for the tendon due to premature slippage from the fixation apparatus before failure. The results of this study fail to support a biomechanical justification for the application of uniform heat treatment to the whole intervertebral disc. Heating annulus fibrosus and nucleus pulposus separately to specific temperatures may have potential clinical benefits.

The FDA has approved the clinical use of recombinant bone morphogenetic proteins (BMPs). However, the use of recombinant BMPs in humans has required large doses of the proteins to be effective, which suggests that the delivery method of bone morphogenetic proteins needs to be optimized. Gene therapy is an alternative method to deliver such recombinant proteins, and gene transfer techniques have been tested on a variety of cell types including bone marrow cells, skin fibroblasts, peripheral blood monocytes, and muscle-derived cells. In this study, we sought to determine the ability of BMP-2-producing human adipose-derived mesenchymal stem cells to heal a critically sized femoral defect in a nude rat model. After approval by the human subjects protection committee, human adipose tissue was obtained from healthy donors. The lipoaspirate was processed as previously described (De Ugarte, D.A., et al. Cells Tissues Organs 174, 101, 2003). Cells were grown in culture and infected with a BMP-2-carrying adenovirus. Five million cells were applied to a collagen- ceramic carrier and implanted into femoral defects as previously described (Zuk, P.A., et al. Mol. Biol. 13, 4279, 2002). All animals were killed at 8 weeks. Femora were dissected out and underwent radiographic, histologic, and biomechanical analysis. Eleven of the 12 femora in the group treated with human processed lipoaspirate (HPLA) cells genetically modified to overexpress BMP-2 had healed at 8 weeks. This was assessed by radiographs, by mechanical testing, and by histology. The one femur that did not heal had a subacute infection. All eight of the femora treated with the rhBMP-2-impregnated collagen-ceramic carrier healed. No statistically significant difference was detected between these two groups. Evaluation of the control groups: group II (collagen- ceramic carrier with HPLA cells) and group III (collagen-ceramic carrier alone) showed that none of the femora had healed by 8 weeks. Our results indicate that HPLA cells genetically modified by adenoviral gene transfer to overexpress BMP-2 can induce bone formation in vivo and heal a critically sized femoral defect in an athymic rat. The HPLA cells alone did not induce significant bone formation. However, when combined with an osteoinductive factor these cells may be an effective method for enhancing bone healing and the tissue engineering of bone.

The purpose of the current study was to help define the role that endoprosthetic reconstructions have in the treatment of metastatic bone disease. Of the 522 endoprostheses implanted at the University of California at Los Angeles (UCLA) between December 1980 and January 2002, 37 (6.9%) were used in 37 patients with metastatic disease. Upper extremity locations outnumbered lower extremity locations 2:1. The 20 males and 17 females ranged in age from 10 to 82 years, with a median age of 54 years. Metastatic renal and breast carcinoma predominated and accounted for 60% of the lesions. The lesion was a primary metastasis in 27 patients (73%,) and a revision of failed previous surgery in 10 patients (27%). Only five patients experienced local complications none of whom required reoperation or amputation. Thirty-three of the 37 patients died of disease progression at a median of 12 months (range, 4-49 months). Function after endoprosthetic reconstruction for metastatic disease is similar to that of function for endoprosthetic reconstructions used for primary malignant tumors, but clearly is dependent on the patient's general condition. Although infrequently used to treat bone metastases, endoprosthetic reconstruction can be a useful alternative reconstruction in selected situations.

This study examined the effect of washer usage on initial pedicle screw fixation and on the salvage of replaced pedicle screws, and the effect of minor adjustments of pedicle screws on insertional torque. Titanium, nontapered pedicle screws (6.5-mm in diameter and 35-mm in length) from one manufacturer and custom-made 5-mm washers were used in the fixation of porcine lumbar spines. Insertional torque was measured with an electronic torque screwdriver and failure strength was determined by straight pullout of the screws using an MTS machine. Initial insertional torque values were significantly greater in pedicle screws placed with washers compared with screws placed without washers. When the screw placed without a washer was salvaged with the addition of a washer, a significant increase in insertional torque resulted. Pullout testing failed to show a significant difference between the screws that were placed with washers and the screws that were placed without washers. In the second part of the experiment, there was a significant decrease in insertional torque after backing out the screw as little as 90 degrees. This current study showed that (1) washers significantly increase the insertional torque of pedicle screws; (2) screws placed without a washer can be salvaged and replaced with a washer, which results in significantly increased insertional torque; and (3) backing out a pedicle screw 90 degrees significantly decreases its insertional torque. Washers can be used with pedicle screws to enhance the initial stability of the screw constructs, and to maximize insertional torque when screws need to be replaced, revised, or adjusted (backed out).

Twenty-five years of clinical and technical advances have shown that the modularity of current endoprostheses provides flexibility for reconstruction and revision, as well as expandability for the skeletally immature. Forging cobalt-chrome stems has enhanced the strength and has resulted in a reduced incidence of fatigue fracture. Extramedullary porous surfaces on the prostheses provide for soft-tissue attachments and extracortical bone bridging. This attachment mechanism effectively isolates the bone–prosthetic interface, from the wear debris that accumulates in the periprosthetic fluid, and reduces the incidence of osteolysis, radiolucent lines, and eventual aseptic loosening. All rotating hinge knee mechanisms defuse the stresses within the prosthesis and at the bone–prosthesis interface. This added degree of freedom helps prevent both fatigue fracture and aseptic loosening. Bushing failures are rare with rotating hinge knee mechanisms as compared with fixed hinge knees. Bipolar components for the hip enhance stability and guard against dislocation when proper attention is given to the capsular repair and the soft-tissue reconstruction. Subsequent acetabular resurfacings have been infrequent. For upper extremity limb-salvage procedures, retention of soft-tissue between the top of the prosthetic humeral head and the overlying acromion is critical in preventing proximal migration and postoperative pain. In those cases where mechanical failure led to revision, function has been maintained. Infected prostheses can be salvaged in 60% of the cases. The Musculoskeletal Tumor Society functional rating for endoprosthetic reconstructions is regularly good to excellent at the knee, good and sometimes excellent at the hip, but usually only fair at the shoulder. These ratings depend on the amount of gluteal muscle remaining or whether or not the deltoid and rotator cuff are retained. For those patients who die early of their disease, endoprosthetic reconstructions appear ideal. For those who survive, good function is enduring, and in the absence of local recurrence or infection, mechanical problems are revisable with excellent prospects of longevity.

Nuttiv, Aurelia M.D.; Chung, Chris M.D.; Kabo, J. Michael Ph.D.; Seeger, Leanne L. M.D. UCLA Author Information

Distal femoral centralizers of five different designs were inserted into model femoral stems and cemented into closed-ended tubes simulating a proximal femoral canal. Specimens underwent cyclic loading from 50 to 500 lb. for 0, 1, 2, 5, and 10 million cycles. Each specimen was then sectioned transversely at multiple levels to obtain serial cross-sections, beginning at the femoral stem tip and proceeding distally so as to include the full extent of the centralizer. The area of each section occupied by a centralizer and the total amount of porosity present in the cement surrounding the centralizers were measured using an image analyzer. A dye penetrant was then applied to each section to visualize cement cracks and areas of incomplete bonding between cement and centralizers. The number, length, and location of cement cracks were catalogued for each section. No cement cracks or lack of bonding was observed at the interface between cement and centralizers. There was greater porosity in the specimens containing centralizers than in controls without centralizers (P < .05). The cement surrounding two of the centralizer designs had a significantly smaller amount of porosity than the cement surrounding the other three designs (P < .05). The number of cracks did not depend on whether a centralizer was used, the type of centralizer, or the cycling duration. In the control specimens, failure to adequately plug the centralizer receptacle hole in the stem tip resulted in very large cement voids.

Distal femoral centralizers of five different designs were inserted into model femoral stems and cemented into closed-ended tubes simulating a proximal femoral canal. Specimens underwent cyclic loading from 50 to 500 lb. for 0, 1, 2, 5, and 10 million cycles. Each specimen was then sectioned transversely al multiple levels to obtain serial cross-sections, beginning at the femoral stem lip and proceeding distally so as to include the full extent of the centralizer. The area of each section occupied by a centralizer and the total amount of porosity present in the cement surrounding the centralizers were measured using an image analyzer. A dye penetrant was then applied to each section to visualize cement cracks and areas of incomplete bonding between cement and centralizers. The number, length, and location of cement cracks were catalogued for each section. No cement cracks or lack of bonding was observed at the interface between cement and centralizers. There was greater porosity in the specimens containing centralizers than in controls without centralizers (P < .05). The cement surrounding two of the centralizer designs had a significantly smaller amount of porosity than the cement surrounding the other three designs (P < .05). The number of cracks did not depend on whether a centralizer was used, the type of centralizer, or the cycling duration. In the control specimens, failure to adequately plug the centralizer receptacle hole in the stem tip resulted in very large cement voids.

Er is dieronderzoek gedaan naar de effecten van passief bewegen op gewrichtsstijfheid, spiermassa en lokale zwelling na een intra-articulaire blessure. Bij dertig volwassen Nieuwzeelandse witte konijnen werden applicaties aan de achterpoten aangebracht voor ofwel passief bewegen ofwel

Management of intraarticular fractures is often complicated by joint stiffness long after bony healing has occurred. The following experiments provide biomechanical evidence for the effectiveness of CPM in maintaining joint function in stabilized articular injuries. The ankles of ten adolescent New Zealand white rabbits were penetrated by Steinmann pins to create an intraarticular injury. One limb of each animal was immobilized, and the contralateral limb was placed in a continuous passive motion (CPM) machine for three weeks. Joint stiffness of each ankle was quantified with an arthrograph before injury and after three weeks of treatment. Hindlimb volumes were recorded before injury and monitored at weekly intervals using a water-displacement method. Joint stiffness increased 2.6 times the preinjury levels in limbs that were immobilized for three weeks. There was no statistically significant increase in joint stiffness in ankles treated with CPM compared to preinjury values. The posttraumatic difference between the CPM-treated and immobilized limbs was highly significant; limb swelling was not affected by CPM.

Dimethyl sulfoxide (DMSO) is an inorganic compound with many interesting in vitro properties, including the ability to scavenge oxygen-free radicals. DMSO has been used to treat a variety of clinical conditions, especially musculoskeletal trauma, but valid data regarding its effectiveness are lacking. This paper reviews the pharmacology of DMSO and reports on its effectiveness in reducing posttraumatic limb swelling and ankle joint stiffness in a rabbit hind limb model. The left and right hind limbs of the test and control animals were instrumented and fractured identically. DMSO was applied daily to the skin of only one limb in the test animals. DMSO reduced postinjury ankle stiffness in both ankles of the test rabbits by 41% but had no effect on limb swelling compared to control rabbits. Postulated mechanisms of decreased joint stiffness include oxygen-free radical scavenging and inhibition of fibroblast proliferation.