Robotic assisted spinal surgery--from concept to clinical practice.

After several years of product development, animal trials and human cadaver testing, the SpineAssist--a miniature bone-mounted robotic system--has recently entered clinical use. To the best of the authors' knowledge, this is the only available image-based mechanical guidance system that enables pedicle screw insertion with an overall accuracy in the range of 1 mm in both open and minimally invasive procedures. In this paper, we describe the development and clinical trial process that has brought the SpineAssist to its current state, with an emphasis on the various difficulties encountered along the way and the corresponding solutions. All aspects of product development are discussed, including mechanical design, CT-to-fluoroscopy image registration, and surgical techniques. Finally, we describe a series of preclinical trials with human cadavers, as well as clinical use, which verify the system's accuracy and efficacy.

Evaluation of a novel tourniquet device for bloodless surgery of the hand.

This study evaluates a new device (S-MART ) for exsanguination and occlusion of the blood flow to the arm for hand surgery. The device consists of a silicone ring wrapped within a sterile stockinette and pull straps. It is applied by placing it on the patient's fingers and rolling it up the limb to the desired occlusion site by pulling on the straps. The time for placement and removal of the device was measured during trigger release and carpal tunnel surgery and the quality of exsanguination was evaluated. The device could be placed and removed quickly and provided an excellent bloodless field. At follow-up examination no signs or symptoms were seen at the site of the S-MART occlusion and no complications were observed in any patient.

The effect of abduction differences between cup and contralateral acetabular angle on polyethylene component wear.

One hundred forty-two patients who underwent cemented or uncemented hip replacement were studied radiographically to determine acetabular component wear. Mean duration of follow-up was 58 months (range: 35-92 months). Average linear wear was 0.78 mm (range: 0-1.9 mm), and average wear rate was 0.16 mm/year (range: 0-0.45 mm/year). An increased wear rate per year correlated with a discrepancy >18.3 degrees between contralateral acetabular angle and acetabular cup inclination (P<.005). Statistical analysis revealed no significant correlation between cup inclination and polyethylene wear, which was studied without considering the contralateral hip (P>.3). There was no relationship between polyethylene wear and cup design, weight, and initial polyethylene thickness.

The effect of intramedullary corticocancellous bone plug for hip hemiarthroplasty.

BACKGROUND: A prospective review was performed on 60 consecutive patients with hip hemiarthroplasty after femoral neck fractures. METHODS: Twenty-two patients underwent Austin Moore hemiarthroplasty with an intramedullary corticocancellous bone plug at the tip of the prosthesis (group A) and 38 patients underwent Austin Moore hemiarthroplasty alone (group B). The patients were evaluated clinically and radiographically at 3 and 6 months postoperatively and annually thereafter. RESULTS: There was no statistically significant difference in thigh pain score between the two groups. At 3- and 6-month follow-up, 88% and 83% of group A patients experienced no pain or mild thigh pain, compared with 72% and 76% in group B, respectively. The radiographs revealed more stem subsidence and calcar osteolysis in group B than in group A (p < 0.01 and p < 0.05, respectively). Furthermore, in both groups there was a correlation between calcar atrophy, stem subsidence, and early clinical thigh pain score (p < 0.05). CONCLUSION: Our data suggest that, whereas the radiologic findings in both groups may be related to thigh pain, they had little effect on the rate of femoral stem revision. We believe that the application of a corticocancellous bone plug in uncemented hip hemiarthroplasty for treatment of femoral neck fractures can decrease the incidence of early thigh pain in the first 6 months.

Hydroxyapatite-coated total hip replacement in Paget's disease: 20 patients followed for 4-8 years.

20 patients, who had had total hip replacements for symptomatic osteoarthrosis secondary to Paget's disease, were followed for a mean of 6 (4-8) years. Proximal hydroxyapatite-coated stems were implanted in all patients. 12 patients received hydroxyapatite-coated, 2 cemented (Muller type) and 6 cementless cups (Morsher type). The mean Harris hip score was 31 (7-40) points preoperatively and 88 (74-100) postoperatively. The radiographic evaluation revealed good stability and fixation using Engh's criteria. One stem subsided early more than 5 mm and then seemed to stabilize. Our findings support the use of hydroxyapatite total hip implants for patients with this disease and osteoarthrosis.

The role of computed tomography in cervical spinal injury due to diving.

We studied both the clinical features and computed tomography (CT) findings in 25 patients with a cervical spinal injury related to diving. In all patients the X-rays, including anteroposterior, lateral and open mouth views, were normal. The clinical features included headache, dizziness, without an alteration in the state of consciousness. In 5 patients, the CT spinal scan revealed cervical spinal injury unrecognised on X-ray. In 4 of them, the mechanism of the trauma was a direct injury to the head when it hit the bottom of the pool; in 1 patient, the mechanism was indirect injury transmitted from the stretched hands to the cervical spine. We conclude that the cervical spinal injury caused by diving should be evaluated selectively by CT spinal scan in patients with direct cervical injury, even if the clinical and roentgenographic results appear negative.

Hydroxyapatite-coated total hip replacements in patients 65 years of age and over.

Prospective review examined 69 patients aged over 65 years (mean: 73 years; range: 65 to 85 years) who underwent 72 primary hydroxyapatite-coated total hip replacements by one surgeon. The femoral component used was titanium alloy coated by hydroxyapatite on the proximal third and the acetabular component was spherical and unthreaded, coated with hydroxyapatite. All patients were evaluated clinically by Harris Hip Score and radiologically using Engh's criteria with a mean follow-up of 86 months (range: 29 months to 10 years). Preoperative radiologic evaluation for osteoporotic bone using the Singh index was performed. Average Harris Hip Score increased from 45 before surgery to 89 at last follow-up. Two femoral and one-acetabular components were shown to probably be loose, but none was definitely loose or unstable by Engh's criteria. There was no correlation between clinical and radiologic results with respect to age, sex, and preoperative diagnosis. In contrast, significant statistical correlation was demonstrated between Charnley groups A or B, and group C, with regard to the Harris Hip Score (p = 0.047). There was no correlation between Charnley groups and radiological results. There was no statistical difference between patients with osteoporotic bone (Singh 1-3) and non-osteoporotic bone (Singh 4-6) with respect to clinical and radiologic evaluation. These early clinical and radiologic results compare favorably with those of hydroxyapatite-coated total hip replacements for younger patients and cemented total hip replacements in older patients. We recommended that hydroxyapatite-coated total hip replacements should not be reserved for younger patients. They can be used safely in patients over 65 years of age, promising minimal postoperative thigh pain and satisfactory clinical and radiologic results.

The effect of intramedullary bone plug on femoral stem migration of hydroxyapatite-coated hip arthroplasty.

This study investigated the effect of intramedullary corticocancellous bone plug on the fixation and stability of hydroxyapatite-coated femoral stems in total hip arthroplasty (THA). Intramedullary corticocancellous bone plug was used in 30 patients with hydroxyapatite-coated femoral stems (group A) and a consecutive series of 30 patients with hypdroxyapatite-coated stems without bone plug served as the control group (group B). Patients underwent clinical and radiographic follow-up for at least 2 years. The addition of corticocancellous bone plug to the hydroxyapatite-coated stem significantly improved clinical and radiographic results. The mean Harris Hip Score at 3 and 6 months postoperatively was 92 and 94 in group A, and 84 and 87 points in group B (P<.004 and P<.001, respectively). There was no significant difference between groups at 1 year postoperatively and thereafter. The predominant cause for the difference was the thigh pain score, which was reduced at both 3 and 6 months in group A compared to group B (P<.01 and P<.05, respectively). There also were statistical differences between the two groups regarding radiographic signs. The evidence of endosteal bone formation in group A patients was superior at 3 and 6 months (P<.001 and P<.01, respectively). The appearance of a radiolucent line was significant in group B patients at 3 and 6 months (P<.001). Femoral stem migration of 3 mm was noted in three group B patients versus no group A patients (P<.05). These short-term clinical and radiographic results suggest corticocancellous bone plug can provide early pain relief and durable implant fixation, but long-term follow-up should be considered.

Intraosseous ganglia of glenoid.

A rare case of intraosseous ganglia of the glenoid in a 35-year-old woman is presented. The patient had painful right shoulder and no limit of motion. Radiographs and computed tomographic scans showed a large lytic lesion involving the entire glenoid bone. The patient was treated by curettage and autocorticocancellous bone graft. Six months after the operation, the patient has an excellent clinical outcome and radiologic sign of integration of the bone graft. Few cases of intraosseous ganglia of the glenoid have been reported, but none with the entire glenoid involvement.

Humeral fracture following shoulder arthroplasty.

Fracture of the humeral shaft after total or hemiarthroplasty of the shoulder occurs infrequently but has serious consequences. This article reports on five patients with ipsilateral humeral fractures following shoulder hemiarthroplasty who were treated either conservatively or surgically. Fractures in the three patients treated conservatively healed on average by 7 months. The results were satisfactory in one patient and unsatisfactory in two patients. Both of these patients complained of pain and limitation of shoulder motion. Fractures in the two patients treated by open reduction and Mennen plate fixation healed on average by 2 months, resulting in a better outcome for these patients treated surgically.

Conservative versus surgical treatment for femoral fracture after total or hemiarthroplasty of hip.

This retrospective study compared internal fixation of a femoral fracture following total or hemiarthroplasty of hip with conservative treatment. Sixteen patients were included in the study and classified according to Johannsen. Seven of these patients were treated conservatively by skeletal traction (group A), while the remaining nine patients underwent internal fixation by Mennen plate in conjunction with bone graft (group B). All patients were followed for at least 2 years and evaluated clinically and radiographically using the Mayo Clinic score. The results of group B were superior to those of group A for fracture lines located proximally or extending distally to the tip of the prosthesis. Furthermore, two patients from group A in whom conservative treatment had failed underwent internal fixation, improving their final outcome. Regarding fracture distal to the tip of the prosthesis, there was no significant difference in final outcome between the groups. Our conclusion is that Mennen plate fixation should be considered the treatment of choice in femoral fracture around the tip of a prosthesis, and Mennen plate fixation for fracture distal to the tip should remain as a good option, especially for patients who would like to reduce the length of postoperative hospitalization.

Cementless coated and noncoated Mathys acetabular cups: radiographic and histologic evaluation.

This study evaluated 185 cementless Mathys coated and uncoated acetabular cups inserted for total hip replacement since September 1984. All of the cups were high-density polyethylene. Sixty were uncoated (group A), 96 were coated with hydroxyapatite (group B), and 29 were coated with titanium (group C). Cup survival was assessed clinically, histologically, and radiographically, and a computer-assisted EBRA method was used to evaluate cup migration. After a mean follow-up of 8 years, five cups in group A that had previously shown migration were revised as a result of aseptic loosening, while no loosening of hip sockets occurred in groups B and C. These results suggest that Mathys cups should be used only if coated with hydroxyapatite or titanium. Furthermore, the histologic evaluation in four cups from groups B and C revealed normal bone formation without inflammation or fibrotic tissue around the cups, promising long-term survival.

Femoral bone reconstruction in revision total hip replacement.

Twelve patients who had undergone total hip replacement complicated by aseptic loosening with severe bone loss were included in this study. Eight of these patients had aseptic loosening of more than the second revision and the remaining four patients of the fourth revision total hip replacement. In all patients, the radiographs revealed an extremely thin cortex around the stem of the prosthesis and almost disappearance of one cortex. All patients were treated by revision total hip replacement in conjunction with Mennen plate fixation and bone graft support. The results were satisfactory in ten patients in respect to functional activity, pain, and radiographic evaluation. In two patients who underwent their fifth revision, the results were unsatisfactory but better than that before the operation. Our conclusion is that Mennen plate fixation provides a sufficient and easy operative technique for the correction of aseptic loosening of total hip prostheses accompanied by severe bone loss.

Urografin injection demonstrated soft tissue ganglion communication with an intraosseous ganglion cyst.

Intraosseous ganglion cysts rarely occur in the hand or wrist. We present a case of a soft tissue ganglion cyst that communicated with the intraosseous ganglion of the scaphoid. Typical diagnostic studies include radiography, computed tomography, and magnetic resonance imaging. The diagnosis was made in this case by injection of Urografin into the soft tissue ganglion. The patient underwent excision of both ganglion cysts, resulting in a satisfactory outcome.

Glenoid fracture: conservative treatment versus surgical treatment.

Glenoid fossa fractures are rare. The indication for conservative or surgical treatment is controversial, especially because of limited reports in the literature. Many authors prefer conservative treatment for most types of glenoid fractures to the alternate surgical treatment, but long-term follow-up is rarely reported. We report on four patients with displaced, intra-articular glenoid fossa, who were treated either surgically or conservatively. After an average 7-year follow-up, clinical and radiographic results were satisfactory in all patients. Based on the literature and our limited experience, we recommend that conservative treatment be considered as a good option for displaced intra-articular glenoid fossa fracture.

Revision arthroplasty of femoral cortex defect using a noncemented stem, Mennen plate, and bone graft.

Twelve patients who underwent total hip replacement complicated by aseptic loosening with severe bone loss were included in this study. Two patients had aseptic loosening of the second revision, six of the third revision, and the remaining four patients of the fourth revision total hip replacement. In all patients, the radiographs revealed an extremely thin cortex around the stem of the prosthesis and almost complete disappearance of one cortex. All patients were treated by revision total hip replacement in conjunction with Mennen plate fixation and allograft bone support. The allograft bone support included three cortical struts and nine massive bone grafts that used cement as a strew. The results were satisfactory in 10 patients in respect to functional activity, pain and radiographic evaluation. In two patients who underwent their fifth revision, the results were unsatisfactory but better than before the operation. Mennen plate fixation provides a sufficient and easy technique for aseptic loosening of total hip replacement with severe bone loss. By preserving the periosteal blood supply, the time required for bone graft incorporation is shortened, resulting in an early final outcome.