In reading “Outcome of Lower-Limb Preservation with an Expandable Endoprosthesis After Bone Tumor Resection in Children,” we are reminded of the quote attributed to Aaron Levenstein: “Statistics are like bikinis. What they reveal is suggestive, but what they conceal is vital.” The article by Henderson et al. is sure to be controversial, which is to be expected given that the authors report on a relatively new surgical technique without well-established indications. We suspect that some readers will question why the article was accepted for publication in The Journal of Bone and Joint Surgery. Others will welcome it as an introduction to a new surgical option for children with a primary malignant bone tumor. Regardless of the reader’s point of view, the authors provide useful information that, although controversial and having substantial limitations, is useful and worthy of publication. It will remain up to the reader to interpret whether the data show that the cup is half full or half empty.
Limb-sparing surgery for primary malignant bone tumors has become a widely accepted and common treatment in skeletally mature patients. In fact, 90% to 95% of all skeletally mature patients with a primary malignancy of bone, as well as many patients near skeletal maturity, are treated with limb-sparing surgery1,2. However, as the authors acknowledge in their introduction, “the optimal treatment of malignant pediatric lower-extremity bone tumors is controversial.” In an effort to address this patient population’s needs, Drs. Henderson, Pepper, Marulanda, Binitie, Cheong, and Letson present their experience with an expandable endoprosthesis.
The first expandable prosthesis was introduced in 19763. Over the past thirty-five years, however, the use of such prostheses has been limited. The present study involved thirty-eight patients who were treated with an expandable endoprosthesis, twenty-six of whom were alive at the time of completion of the study. Patient age at the time of the surgery ranged from four to fifteen years, with a mean age of 10.4 years. The mean duration of follow-up of the twenty-six surviving patients was forty-eight months (range, twenty-three to 146 months). Fifteen of these patients had reached skeletal maturity and completed the prosthesis lengthening process. Lengthening of 2 to 13 cm was achieved, with a mean final limb-length discrepancy of 0.7 cm (range, 0 to 2 cm). However, the complication rate was substantial. Forty-two percent of patients experienced one or more complications, including ten patients who required prosthesis revision and two who required amputation.
The critical reader will note the obvious limitations of this study. It is retrospective, and the functional data were obtained through inconsistent means (telephone conversations, mailed surveys, and clinical examinations). Limb length was assessed by clinical examination performed by one of three unblinded providers (two surgeons and a physical therapist) rather than with radiographs. Additionally, the study involves three different prosthesis designs in five different anatomic sites (proximal femoral, total femoral, distal femoral, proximal tibial, and distal tibial). Finally, the outcome data are incomplete, with only 58% of patients having completed the Pediatric Outcomes Data Collection Instrument (PODCI).
Some readers will interpret the data as showing that “the cup is half empty.” They will question the rationale as well as the emotional and financial cost of using expandable prostheses in children. Is this an example of technology over reason? Do the results justify the current complication rate? Does use of such a prosthesis offer an advantage over other, more established techniques such as amputation and/or contralateral epiphysiodesis? Asking such questions is not only justified but essential in the advancement of surgical techniques. At the same time, other readers will interpret the data as showing that “the cup is half full” and will ask whether this study shows useful information that warrants further investigation.
Ultimately, the answers depend on whether or not the reader can see what is suggestive and what is concealed in the article. Like many new techniques, expandable prostheses for children will be refined, modified, and improved on. I believe that, despite the limitations, the article by Henderson et al. suggests the existence of a role for expandable prostheses and limb-preserving surgery in children with primary malignant bone tumors. This article and future publications are needed to answer the question of exactly what that role will be.