How Can We Differentiate Local Recurrence From Heterotopic Ossification After Resection and Implantation of an Oncologic Knee Prosthesis in Patients with a Bone Sarcoma?

Clinical value of ultrasound for the evaluation of local recurrence of primary bone tumors

Background

Early detection of local recurrence would improve the survival rate of patients with recurrent bone tumors. There is still no consensus on how to follow up after surgery of primary malignant bone tumors. Therefore, the purpose of this study is to evaluate the diagnostic value of ultrasound (US) for local recurrence after limb salvage by comparing it with other imaging modalities.

Methods

We retrospectively reviewed the medical records of patients who were regularly examined by US in our hospital after primary bone tumor surgery from January 2016 to December 2019, some of which underwent x-ray, computed tomography (CT), or ⁹⁹mTc-MDP bone scan. Recurrence was determined by pathologic confirmation. The cases were considered a true negative for no recurrence if no clinical or pathologic evidence for recurrence was found at least 6 months after the US examination. The Chi-square test or Fisher exact test was used to compare categorical data. p-values < 0.0083 were considered statistically significant.

Results

A total of 288 cases were finally enrolled in our research, including 66 cases with pathologic results. The sensitivity of US was 95.0%, higher than that of x-ray (29.6%) (p = 0.000). The accuracy of US was 96.9%, higher than that of x-ray (85.6%) (p = 0.000).

Conclusion

As a nonradiative and cost-effective examination, US may be used as a routine imaging method for postoperative surveillance of primary bone tumors, especially those with metal implants, if more multicenter prospective studies can be done in the future.

A new prognostic nomogram for heterotopic ossification formation after elbow trauma : the Shanghai post-Traumatic Elbow Heterotopic Ossification Prediction (STEHOP) model

AIMS

Heterotopic ossification (HO) is a common complication after elbow trauma and can cause severe upper limb disability. Although multiple prognostic factors have been reported to be associated with the development of post-traumatic HO, no model has yet been able to combine these predictors more succinctly to convey prognostic information and medical measures to patients. Therefore, this study aimed to identify prognostic factors leading to the formation of HO after surgery for elbow trauma, and to establish and validate a nomogram to predict the probability of HO formation in such particular injuries.

METHODS

This multicentre case-control study comprised 200 patients with post-traumatic elbow HO and 229 patients who had elbow trauma but without HO formation between July 2019 and December 2020. Features possibly associated with HO formation were obtained. The least absolute shrinkage and selection operator regression model was used to optimize feature selection. Multivariable logistic regression analysis was applied to build the new nomogram: the Shanghai post-Traumatic Elbow Heterotopic Ossification Prediction model (STEHOP). STEHOP was validated by concordance index (C-index) and calibration plot. Internal validation was conducted using bootstrapping validation.

RESULTS

Male sex, obesity, open wound, dislocations, late definitive surgical treatment, and lack of use of non-steroidal anti-inflammatory drugs were identified as adverse predictors and incorporated to construct the STEHOP model. It displayed good discrimination with a C-index of 0.80 (95% confidence interval 0.75 to 0.84). A high C-index value of 0.77 could still be reached in the internal validation. The calibration plot showed good agreement between nomogram prediction and observed outcomes.

CONCLUSION

The newly developed STEHOP model is a valid and convenient instrument to predict HO formation after surgery for elbow trauma. It could assist clinicians in counselling patients regarding treatment expectations and therapeutic choices. Cite this article: Bone Joint J 2022;104-B(8):963-971.

Does the adherence of distal femur parosteal osteosarcoma to the neurovascular bundle increase the rate of local recurrences?

BACKGROUND

Proximity of tumor to the neurovascular bundle (NVB) makes achieving a wide margin difficult. In low-grade parosteal osteosarcoma (POS), it is not clear whether adherence of tumor to NVB increases the rate of local recurrence (LR). In this study, we evaluated whether tumor adherence to the NVB increases the risk of LR in low-grade POS of the distal femur?

HYPOTHESIS

We hypothesized that if the thin neurovascular barrier (the adventitia of the vessels and the epineurium of the nerve) prevents tumor penetration, the rate of LR should be comparable between the lesions with and without a continuous layer of healthy fatty tissue between the tumor and NVB.

MATERIALS AND METHODS

In a retrospective survey, 30 patients with low-grade POS of the posterior aspect of the distal femur were evaluated for the proximity of mass to NVB. Based on the proximal to distal T1 axial MRI sections, the tumors were divided into two groups including the tumors with an uninterrupted (group A) and interrupted (group B) rim of fatty tissue between the mass and NVB. The rate of LR was compared between the two study groups. The concordance of MRI in detecting NVB adherence was checked with pathology specimen.

RESULTS

Using MRI, we identified 16 cases in group A and 14 cases in group B. The MRI status of fatty rim was concordant with pathology specimen in 96.4% of cases. The mean follow-up period of the two groups was not statistically different (117±27.6 vs. 105.8±29.4 months, respectively, p=0.29). The other baseline characteristics of the two groups were statistically comparable, as well. The rate of LR was 12.5% (2 out of 16 patients) in group A and 14.3% (2 out of 14 patients) in group B (95% CI: 0.142-9.586, p=0.87). The 10-year recurrence-free survival was 87.5% for group A and 85.7% for group B (p=0.9).

DISCUSSION

The absence of a continuous rim of fatty tissue between the tumor and NVB in MRI does not increase the risk of LR in low-grade POS of the distal femur.

LEVEL OF EVIDENCE

IV.