Calcium sulfates: what is the evidence?

Calcium sulphate has been used extensively as a bioabsorbable bone substitute for 90 years. Its advantages include its low cost, ready availability and unlimited supply, lack of donor site morbidity, use as a delivery vehicle for other compounds (especially antibiotics), inherent osteoconductive properties (based on a structure similar to bone), and its proven safety record. We sought to determine the evidence-based medical studies (prospective and/or randomized clinical trials) that support the use of calcium sulphate as a bioabsorbable bone substitute. At the present time, the majority of reports are basic science investigations, animal studies, and retrospective clinical reviews of varying degrees of quality. Multiple retrospective reviews reveal that calcium sulphate is an effective void-filler in contained bony defects such as metaphyseal voids after impacted fracture reduction (calcaneus, tibial plateau), simple bone cysts, or posttraumatic defects. Three case series examining the use of calcium sulphate in the treatment of bone nonunions revealed a significant failure rate, suggesting that this material, used in isolation, is not optimal to promote union in that setting. A low but consistent complication rate, specifically serous drainage from the wound as the calcium sulphate absorbs, has been reported. This complication is higher when the material is used in higher volumes (greater than 20 mL) or in subcutaneous bones (tibia, ulna). There is some Level I to II evidence (one randomized trial, one case-control study, one prospective cohort study) that antibiotic-impregnated bioabsorbable calcium sulphate has the potential to reduce the number of procedures and surgical morbidity associated with the surgical treatment of chronic osteomyelitis and infected nonunion while maintaining a high rate of infection eradication. Calcium sulphate remains an inexpensive, safe, reliable bone void filler that can also serve as a absorbable delivery vehicle for antibiotics or other compounds. Further high-quality randomized and prospective clinical trials are required to define the role of calcium sulphate in modern orthopaedics.

Open reduction and internal fixation compared with circular fixator application for bicondylar tibial plateau fractures. Surgical technique.

BACKGROUND: Standard open reduction and internal fixation techniques have been successful in restoring osseous alignment for bicondylar tibial plateau fractures; however, surgical morbidity, especially soft-tissue infection and wound necrosis, has been reported frequently. For this reason, several investigators have proposed minimally invasive methods of fracture reduction followed by circular external fixation as an alternative approach. To our knowledge, there has been no direct comparison of the two operative approaches. METHODS: We performed a multicenter, prospective, randomized clinical trial in which standard open reduction and internal fixation with medial and lateral plates was compared with percutaneous and/or limited open fixation and application of a circular fixator for displaced bicondylar tibial plateau fractures (Schatzker types V and VI and Orthopaedic Trauma Association types C1, C2, and C3). Eighty-three fractures in eighty-two patients were randomized to operative treatment (forty-three fractures were randomized to circular external fixation and forty to open reduction and internal fixation). Follow-up consisted of obtaining a history, physical examination, and radiographs; completion of the Hospital for Special Surgery (HSS) knee score, the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the Short Form-36 (SF-36) General Health Survey; and recording of complication and reoperation rates. RESULTS: There were no significant differences between the groups in terms of demographic variables, mechanism of injury, or fracture severity and/or displacement. However, patients in the circular fixator group had less intraoperative blood loss than those in the open reduction and internal fixation group (213 mL and 544 mL, respectively; p = 0.006) and spent less time in the hospital (9.9 days and 23.4 days, respectively; p = 0.024). The quality of osseous reduction was similar in the groups. There was a trend for patients in the circular fixator group to have superior early outcome in terms of HSS scores at six months (p = 0.064) and the ability to return to preinjury activities at six months (p = 0.031) and twelve months (p = 0.024). These outcomes were not significantly different at two years. There was no difference in total arc of knee motion, and the WOMAC scores at two years after the injury were not significantly different between the groups with regard to the pain (p = 0.923), stiffness (p = 0.604), or function (p = 0.827) categories. The SF-36 scores at two years after the injury were significantly decreased compared with the controls for both groups (p = 0.001 for the circular fixator group and p = 0.014 for the open reduction and internal fixation group), although there was less impairment in the circular fixator group in the bodily pain category (a score of 46) compared with the open reduction and internal fixation group (a score of 35) (p = 0.041). Seven (18%) of the forty patients in the open reduction and internal fixation group had a deep infection. The number of unplanned repeat surgical interventions, and their severity, was greater in the open reduction and internal fixation group (thirty-seven procedures) compared with the circular fixator group (sixteen procedures) (p = 0.001). CONCLUSIONS: Both techniques provide a satisfactory quality of fracture reduction. Because percutaneous reduction and application of a circular fixator results in a shorter hospital stay, a marginally faster return of function, and similar clinical outcomes and because the number and severity of complications is much higher with open reduction and internal fixation, we believe that circular external fixation is an attractive option for these difficult-to-treat fractures. Regardless of treatment method, patients with this injury have substantial residual limb-specific and general health deficits at two years of follow-up.

Effect of distal humeral varus deformity on strain in the lateral ulnar collateral ligament and ulnohumeral joint stability.

BACKGROUND: Recent reports have implicated cubitus varus deformity as a risk factor for the development of late posterolateral rotatory instability of the elbow. The purpose of this study was to determine the biomechanical relationship between cubitus varus and strain in the lateral ulnar collateral ligament and subluxation of the ulnohumeral joint as it relates to posterolateral rotatory instability. METHODS: Eleven fresh-frozen cadaveric elbow joints were mounted in an apparatus that allowed active elbow motion. Supracondylar osteotomies were performed to create cubitus varus deformities of 0 degrees to 30 degrees in 5 degrees increments. Each elbow was loaded with a supination moment of 1.2 Nm and a resistive triceps extension force. Strain in the lateral ulnar collateral ligament and widening of the ulnohumeral joint were measured at each position of varus, and the resulting strain and joint-widening values were averaged. RESULTS: Strain in the lateral ulnar collateral ligament was found to increase as the cubitus varus deformity increased. Likewise, the ulnohumeral joint space was seen to progressively widen with increasing cubitus varus. Strain was significantly increased at 30 degrees of varus deformity (p = 0.03), and widening of the ulnohumeral joint space was significantly increased at 25 degrees of varus deformity (p = 0.004). When differences in the size of the cadaveric specimens were accounted for in an analysis of covariance, ligament strain was significantly increased at 25 degrees of varus (p = 0.005) and widening of the ulnohumeral joint space, at 20 degrees (p = 0.01). CONCLUSIONS: Cubitus varus deformity of the elbow increases strain in the lateral ulnar collateral ligament, with a corresponding increase in ulnohumeral joint-opening consistent with the posterolateral rotatory instability of the elbow seen clinically.

Changes in alignment of the scoliotic spine in response to lateral bending.

STUDY DESIGN: A retrospective cross-sectional review studied the posteroanterior and lateral bending radiographs of 26 preoperative patients with thoracic major adolescent idiopathic scoliosis. OBJECTIVE: To characterize the relation of vertebral axial rotation, apparent vertebral wedging, and disc wedging with lateral bending in patients with severe adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Lateral bending radiographs are used commonly in surgical planning to assess the flexibility of the spine and to establish the placement of instrumentation. However, their use in the assessment of motion in the axial plane has not been clearly established. METHODS: Data were collected retrospectively from 26 subjects immediately before spinal surgery. All the subjects had adolescent idiopathic scoliosis with right thoracic major curves. Axial rotation, vertebral wedging, and disc wedging were measured from T4 to L4 on left and right supine bending and standing posteroanterior radiographs. The apexes of the major and minor curves, the neutral vertebrae, and the Cobb angles were recorded. RESULTS: No significant differences in axial rotation were found at the thoracic apex, neutral vertebrae, or lumbar apex in response to lateral bending. Most of the wedging occurs in the disc, and is maximal at the apex of the curve. The total amount of wedging was higher in more severe curves. CONCLUSIONS: Lateral bending does not improve axial rotation in severe scoliosis (scoliosis for which surgical correction is advised). Structural changes including disc and vertebral wedging may be responsible for the lack of rotational correction of the scoliotic spine. Lack of axial flexibility in the thoracic region may hamper surgical attempts to correct the deformities of the trunk.