Aim

The purpose of this study was to report on outcomes after stabilization of large skeletal defects following radical debridement of hip or knee infections and staged reimplantation using segmental antibiotic mega-spacers.

Limb salvage in musculoskeletal tumor surgery may be complicated by infection. With the advent of modern techniques and medical management limb sparing surgeries can be considered as an alternative to ablation.

Between 1992 and 2014, 17 patients were treated for infected megaprostheses after being surgically treated for musculoskeletal tumors. There were nine females and eight males. The mean time from the index procedure until infection was 30 months. Following radical debridement, the resultant skeletal defect averaged 30 cm. Patients were treated with local antibiotics in polymethyl methacrylate (PMMA) spacers and endoprostheses as well as IV antibiotics for a minimum of six weeks followed by oral antibiotics for an additional six weeks. The initial tumor procedure involved the femur in eleven patients, the tibia in two, the acetabulum in one, the humerus in two, and the ulna in one. Patients had repeat cultures before two-stage reimplantation when their WBC, ESR, and CRP returned to normal. Patients were reimplanted when final cultures were negative.

Thirteen patients were treated using a two-stage protocol with customized intraoperative antibiotic impregnated PMMA spacers including intramedullary nails for a mean of 10 months and the other four patients had a one-stage procedure. These four patients included two patients with a total femur replacement and two patients with an allograft-prosthetic composite of the proximal humerus and ulna. The organisms cultured were gram positive in 14 cases, mixed gram positive and negative in one case, and two patients had no growth on cultures but histologic evidence of acute infection. Reimplantation was successful in 13 patients after the initial procedure (76%). Four patients had recurrent infections. One of these patients was successfully reimplanted after a one-stage procedure, two had a second two-stage procedure and have retained their spacers, and one had an amputation. Successful limb salvage in regards to infection control occurred in 14/17 patients (82%). One additional patient required an amputation for an oncologic complication (local recurrence), so the overall limb salvage rate was 13/17 (76%).

Patients with megaprosthetic infections following limb salvage treatment for musculoskeletal tumors do not have to be uniformly subject to amputation. Radical debridement and appropriate antibiotics in conjunction with custom spacers followed by selective one- and two-stage reimplantation results in successful limb salvage in 82% of patients. This result is similar to other reports despite the large size average defects.

In patients requiring two-stage procedures, stabilization of large skeletal defects after radical debridement must be attained in order to successfully treat the infection. With the use of standard rod plus antibiotic impregnated PMMA spacers limb salvage may be attempted with satisfactory results.

Between 1992 and 2014, 23 patients were treated for hip, knee, or shoulder musculoskeletal infections resulting in an average skeletal defect of 22 cm. There were 13 males and 10 females. Twelve patients had infected tumor prostheses, seven patients had an infected total joint arthroplasty, and four patients had a primary infection involving a large skeletal defect. The mean time from the index procedure until infection was 22 months. Following debridement, the defect was stabilized with Tobramycin and Vancomycin impregnated PMMA and intramedullary nails. Patients were treated with IV and oral antibiotics for six weeks each. In 18 patients who had resection about the knee stabilization was achieved with a single femoral or tibial nail in nine patients and with two nails joined by a screw or cerclage wire in the other nine. In four patients a cephalomedullary femoral nail was used for stabilization after resection of the proximal or total femur. One patient had a custom total humeral prostalac using threaded Steinmann pins and 16-gauge wire.

The organisms cultured were gram positive in 19 cases, mixed gram positive and fungal in one, mixed gram negative and mycobacterium in one, and two patients had no growth on cultures but histologic evidence of acute infection. Of the 23 patients, 16 were successfully reimplanted following the initial procedure (70%) and seven had recurrent infections. Three patients with recurrent infections were successfully reimplanted after an additional one-stage procedure and four patients were not reimplanted. Two of these four had amputations and the other two had a second two-stage procedure and have retained their spacers. There were seven complications including a broken spacer, three periprosthetic fractures, two contractures, and one case of aseptic loosening. Successful limb salvage with infection control was 19/23 (83%). One patient required an amputation for local recurrence of their tumor. The overall limb salvage rate was 18/23 (78%).

Stable temporary antibiotic laden cement spacers, made in conjunction with standard intramedullary nails, can provide the necessary limb stability to treat musculoskeletal infections and allow for reimplanation of tumor prostheses for limb salvage.