Biomechanical Motion Changes in Adjacent and Noncontiguous Segments Following Single-Level Anterior Cervical Discectomy and Fusion: A Computed Tomography-Based 3D Motion Capture Study.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) is known to elicit adverse biomechanical effects on immediately adjacent segments; however, its impact on the kinematics of the remaining nonadjacent cervical levels has not been understood. This study aimed to explore the biomechanical impact of ACDF on kinematics beyond the immediate fusion site. We hypothesized that compensatory motion following single-level ACDF is not predictably distributed to adjacent segments due to compensation from noncontiguous levels. METHODS: Six fresh-frozen cervical spines (C2-T1) underwent fluoroscopic screening and sagittal and coronal reformats from computed tomography scans and were utilized to grade segmental degeneration. Each specimen was tested to 30° of flexion and extension intact and following single-level ACDF at the C5-C6 level. The motions of each vertebral body were tracked using 3-dimensional (3D) motion capture into an inverse kinematics model, facilitating correlations between the 3D reconstruction from computed tomography images and the 3D motion capture data. This model was used to calculate each level's flexion/extension range of motion (ROM). RESULTS: Single-level fusion at the C5-C6 level across all specimens resulted in a significant motion reduction of -6.8° (P = 0.002). No significant change in ROM occurred in the immediate adjacent segments C4-C5 (P = 0.07) or C6-C7 (P = 0.15). Hypermobility was observed in 2 specimens (33%) exclusively in adjacent segments. In contrast, the other 4 spines (66%) displayed hypermobility at noncontiguous segments. Hypermobility occurred in 42% (5/12) of the adjacent segments, 28% (5/18) of the noncontiguous segments, and 50% (3/6) of the cervicothoracic segments. CONCLUSION: Single-level ACDF impacts ROM beyond adjacent segments, extending to noncontiguous levels. Compensatory motion, not limited to adjacent levels, may be influenced by degenerative changes in noncontiguous segments. Surprisingly, hypermobility may not occur in adjacent segments after ACDF. CLINICAL RELEVANCE: Overall, the multifaceted biomechanical effects of ACDF underscore the need for a comprehensive understanding of cervical spine dynamics beyond immediate adjacency, and it needs to be taken into consideration when planning single-level ACDF.

Embolization of hypervascular bone metastases reduces intraoperative blood loss: a case-control study.

BACKGROUND: Small case series suggest that preoperative transcatheter arterial embolization minimizes bleeding and facilitates surgery for hypervascular metastatic bone tumors. However, control groups would make our confidence in clinical recommendations stronger, but small patient numbers make prospective trials difficult to conduct on this topic. QUESTIONS/PURPOSES: In this case-control study, we asked whether (1) patients who undergo embolization have less estimated blood loss and/or shorter operative time than patients who do not have embolization; (2) larger tumor size, greater initial tumor vascularity, and longer interval from embolization to surgery are associated with greater estimated blood loss and packed red blood cell transfusion volume; and (3) embolization does not affect renal function in patients with normal preoperative renal function. METHODS: We retrospectively reviewed records of patients with hypervascular bone metastases treated at our institution between 1998 and 2008. Twenty-seven patients with renal cell carcinoma and 12 with thyroid carcinoma who underwent embolization before 41 surgical procedures were matched to 41 patients who did not have embolization with respect to age, diagnosis, tumor size and potential vascularity, and procedure type; matching was performed without knowledge of outcomes. In univariate and multivariate analyses, age, tumor size, use of embolization, surgery type and risk, embolization-to-surgery interval, and degree of devascularization were evaluated for correlations with estimated blood loss, packed red blood cell transfusion volume, operative time, and postembolization renal function. RESULTS: Overall, patients who had embolization had less mean estimated blood loss (0.90 versus 1.77 L; p = 0.002), packed red blood cell transfusion volume (2.15 versus 3.56 U; p = 0.020), and operative time (3.13 versus 3.91 hours; p < 0.001). Larger tumor size correlated with greater estimated blood loss (r = 0.451; p = 0.003), packed red blood cell transfusion volume (r = 0.50; p = 0.002), and operative time (r = 0.595; p < 0.001). Neither the interval for embolization to surgery nor the degree of devascularization correlated with estimated blood loss or transfusion volume. In open rodding with intralesional curettage, transcatheter arterial embolization was associated with reduced estimated blood loss, transfusion volume, and operative time. Packed red blood cell transfusion volume was not reduced by embolization in intramedullary nailing procedures with the patient numbers available. Among patients with normal preoperative renal function who had embolization, creatinine levels remained normal. Mild transient, reversible renal function change occurred in one patient with preoperatively abnormal renal function. CONCLUSIONS: This study suggests that preoperative embolization probably reduces estimated blood loss, particularly for large tumors and during open femoral procedures.

A Systematic Review and Meta-Analysis of En-Bloc vs Intralesional Resection for Giant Cell Tumor of Bone of the Distal Radius.

INTRODUCTION: Surgical management of Giant Cell Tumor of Bone of the distal radius (GCTDR) remains controversial due to risk of local recurrence (LR) offset by functional limitations which result from en-bloc resection. This study aims to determine the oncologic and functional outcomes of wide excision (WE) vs intralesional curettage (IC) of GCTDR. METHODS: A complete search of the applicable literature was done. Included studies reported on patients from the same cohort who were surgically treated for GCTDR with WE or IC. Two reviewers independently assessed all papers. The primary outcome measure was LR. RESULTS: One-hundred-forty-one patients from six studies were included: 60 treated with WE, and 81 with IC. Five WE patients (8%) suffered LR whereas 25 IC patients (31%) did. The odds of LR were three times less in the WE group vs the IC group. MSTS1993 scores, where available, were on average 'good' with WE and 'excellent' with IC. CONCLUSIONS: Within statistical limitations the data support an attempt, where feasible, at wrist joint preservation and superior function with IC. Intralesional curettage is reasonable when the functional benefit outweighs the risk of recurrence as is the case in many cases of GCT of the distal radius.

Functional results following vascularized versus nonvascularized bone grafts for wrist arthrodesis following excision of giant cell tumors.

PURPOSE: Wrist arthrodesis after resection of a giant cell tumor of the distal radius can be performed using a vascularized free fibular transfer (VFFT) or a nonvascularized structural iliac crest transfer (NICT). The purpose of this study was to compare the union times, functional outcomes, and complications after these procedures. METHODS: We identified 27 patients at 2 centers: 14 underwent VFFT, and 13 NICT. The 2 groups were comparable for age, sex, and tumor grade. We assessed functional outcomes of the wrist with the Toronto Extremity Salvage Score, Musculoskeletal Tumor Society 1987 and 1993 scores, and Disabilities of the Arm, Shoulder, and Hand scores. RESULTS: Two local recurrences occurred in the VFFT group and 1 in the NICT group. The VFFT group had 3 patients who had already undergone or were planning to undergo surgery for improved appearance, hardware removal, or tendon release. In the NICT group, 2 infections required debridement, one of which went on to free fibular transfer, but there were no reoperations for nonunion or donor site morbidity. The surgical time was significantly shorter for NICT. Functional scores showed no differences between groups on any of the parameters studied for the upper limb. CONCLUSIONS: Both VFFT and NICT were effective surgical techniques for wrist fusion after distal radial resection for giant cell tumor. Vascularized free fibular transfer should be considered when a major skin defect is anticipated, because it allows the inclusion of a vascularized skin paddle, or when the osseous defect is too long (> 10 cm) for NICT. We were unable to demonstrate a difference in upper limb functional scores between VFFT and NICT. Because the surgical time is significantly shorter and the reoperation rate is lower for NICT, we recommend NICT whenever possible. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic III.