Can Orthopedic Oncologists Predict Functional Outcome in Patients with Sarcoma after Limb Salvage Surgery in the Lower Limb? A Nationwide Study


Limb salvage surgery (LSS) rather than amputation is the operation of choice in 70–85% of all malignant bone and soft tissue lower limb sarcomas.Since the oncological results for amputation and LSS in the surgical treatment of sarcomas are comparable.the decision to perform an amputation or LSS is based on the tumor size, the tumor location, patient preferences, the expected risk of complications and multiple reoperations, and the expected functional outcome . If it is surgically possible, LSS is generally the preferred treatment, unless a poor functional outcome is expected. It has been shown that the functional outcome of LSS is superior to amputation, with the exception of below-knee amputation, which yields a similar function as limb salvage. The expected functional outcome of patients after LSS is thus an important part of the preoperative decision making process for the surgical treatment.

Accurate predictions of functional outcome after limb salvage surgery (LSS) in the lower limb are important for several reasons, including informing the patient preoperatively and, in some cases, deciding between amputation and LSS. This study aimed to elucidate the correlation between surgeon-predicted and patient-reported functional outcome of LSS in the Netherlands. Twenty-three patients (between six months and ten years after surgery) and five independent orthopedic oncologists completed the Toronto Extremity Salvage Score (TESS) and the RAND-36 physical functioning subscale (RAND-36 PFS). The orthopedic oncologists made their predictions based on case descriptions (including MRI scans) that reflected the preoperative status. The correlation between patient-reported and surgeon-predicted functional outcome was “very poor” to “poor” on both scores ( values ranged from 0.014 to 0.354). Patient-reported functional outcome was generally underestimated, by 8.7% on the TESS and 8.3% on the RAND-36 PFS. The most difficult and least difficult tasks on the RAND-36 PFS were also the most difficult and least difficult to predict, respectively. Most questions had a “poor” intersurgeon agreement. It was difficult to accurately predict the patient-reported functional outcome of LSS. Surgeons’ ability to predict functional scores can be improved the most by focusing on accurately predicting more demanding tasks.

This national survey aimed to investigate how well orthopedic oncologists are able to predict the patient-reported functional outcome of patients that had undergone LSS in the lower limb. We found “very poor” to “poor” correlations between patient-reported outcomes and surgeon-predicted outcomes on both the TESS and the RAND-36 PFS. The orthopedic oncologists tended to underestimate patient-reported functional outcome on both scales. The most difficult tasks on the RAND-36 PFS were also the most difficult to predict, whereas, for the least difficult tasks, it was easy to predict that these could be performed without substantial limitations by nearly all patients. The intersurgeon agreement on the RAND-36 PFS questions was mostly “poor” but was “good” for some of the most and least demanding tasks. None of the potentially predicting factors were related to the primary outcome measures.

Our results indicate that it was difficult for the participating orthopedic oncologists to accurately predict the patient-reported functional outcome of limb salvage surgery. On the TESS, for instance, the coefficients of determination () between patient-reported and surgeon-predicted outcomes were lower than 0.20, indicating that less than 20% of the variance in TESS could be explained by the predictions made by the orthopedic oncologists. We did not expect such a poor predictive ability, considering the experience level of the orthopedic oncologists with limb salvage surgery. Several aspects may underlie this seemingly rather poor predictive ability.

First, each limb salvage patient presents a unique case in terms of anatomical involvement. Even in patients with the same type of tumor at a similar location, for instance, the distal femur, final functional results can differ to a large extent. In part, this depends on the amount and precise location of soft tissue involvement, which may have been difficult to see from the limited set of MRI images in the case files. Moreover, patients are unique in terms of adaptive capacity. The adaptation of the patient to the new anatomical and sensorimotor situation plays a large role in the recovery of function.The amount of adaptive capacity may have been hard or impossible to estimate by the orthopedic oncologists from the case files. Second, we measured functional outcome with questionnaires, which are inherently subjective. Thus, the patients’ own perception of functioning may have played a large role in the functional outcome score. It might be that functional outcome measured by objective means, such as, for example, gait analysis, more closely reflects the orthopedic oncologists’ predictions. Third, in the case files, we mimicked as well as possible the information typically available preoperatively to the surgeon in a clinical setting, but the study design did not permit the independent surgeons to review the medical history of the patients nor perform a physical examination before the surgery. As such, predictions of patient-reported functional outcome in a “real” clinical setting (e.g., including a physical examination) might be more accurate than those made in this study. Fourth, patients who had a bone tumor with an intact cortical bone were not included; the patient-reported functional outcome in those patients would potentially have been less difficult to predict than that in the patients with larger tumors.

The poor predictive ability raises the question of which other factors determine functional outcome in limb saving surgery and to what degree. Davis et al. showed that large tumor size, deep lesions, high grade tumor, use of radiotherapy, bone resection, and motor nerve sacrifice are significantly related to increased disability on the TESS . In their study, those combined parameters were able to predict 20% of the variance in TESS score. This is in the same order of magnitude as the presently reported results, indicating that the surgeons were unable to “add” predictive value on top of the given parameters in the case files. The rehabilitation protocol may also have an effect on functional outcome; Shehadeh et al. showed that adherence to a strict rehabilitation protocol after limb salvage surgery led to a relatively high level of functional outcome compared with other studies . If we interpret our findings concurrent with those of Davis et al. and Shehadeh et al., it appears that still a large percentage of functional outcome cannot be predicted by the surgeon nor by anatomical and surgery or adjuvant therapy-related factors nor by rehabilitation protocols. Other factors that may play a significant role in the patient-reported functional outcome include the preoperative physical and mental state of the patient. For example, a patient who is highly motivated and athletic may recover to a far higher level of functioning than one who is less motivated and leads a sedentary lifestyle. From this perspective, one may intuitively expect a correlation between patient-reported functional outcome and age or BMI, but we did not find this . Further studies are required to clarify the role each factor plays in patient-reported functional outcome after limb salvage surgery.




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