John D. Bennett

Arthroscopic diagnosis of intra-articular soft tissue injuries associated with distal radial fractures

Arthroscopy was used to assess the soft tissue injuries associated with distal radial fractures in 118 acute intra- and extra-articular fractures. The triangular fibrocartilage complex (TFCC) was torn in 46 of 118 patients--in 35% of intra-articular fractures and in 53% of extra-articular fractures. No correlation between ulnar styloid fractures and TFCC injuries could be found. Scapholunate (SL) ligament injuries with instability were present in 21.5% of intra-articular fractures and in 6.7% of extra-articular fractures. Lunotriquetral (LT) ligament injuries with instability were present in 6.7% of intra-articular fractures. and in 13.3% of extra-articular fractures. Combined SL and LT injuries were present in 5.6% of intra-articular fracture. Preoperative radiographs correlated with TFCC injury. Patients with TFCC tears had greater shortening and dorsal angulation on the preoperative radiographs. Preoperative radiographs had no predictive value for interosseous ligament injury. Ligamentous injuries are commonly associated with both intra-articular and extra-articular distal radial fractures.

Measurement of the scaphoid humpback deformity using longitudinal computed tomography: Intra- and interobserver variability using various measurement techniques

The intra- and interobserver variability of 3 techniques for measuring the humpback deformity of 37 scaphoids using longitudinal computed tomography was assessed. The 3 measuring techniques were the lateral intrascaphoid angle, the dorsal cortical angle, and the height-to-length ratio. The intraobserver reliability of the intrascaphoid angle was poor; the dorsal cortical angle was moderate to excellent, and the height-to-length ratio was excellent. The interobserver reliability of the intrascaphoid angle was poor to moderate, the dorsal cortical angle was moderate to excellent, and the height-to-length ratio was moderate to excellent. For all 3 observers, the intra- and interobserver reliability was the best for the height-to-length ratio and worst for the intrascaphoid angle. The height-to-length ratio is the most reproducible method of assessing the humpback deformity. Clinical correlation is required to establish whether the height-to-length ratio will be of value in predicting the outcome of fractures of the scaphoid.

Longitudinal computed tomography of the scaphoid: a new technique

Computed tomography is increasingly utilized for the evaluation of scaphoid fracture, nonunion, and deformity. We have developed a new technique of positioning patients while performing longitudinal computed tomography of the scaphoid. With the wrist positioned in radial deviation and neutral flexion, greater patient comfort is provided and immobilization of the wrist is not required. A reproducible image can be obtained with attention to the alignment of the scanning plane to the longitudinal axis of the scaphoid on the scout image, and verified with the “target sign”. High resolution images, which clearly demonstrate the abnormalities of the scaphoid, can be produced even if the patient has a cast on the wrist or if there is hardware in situ.

Effect of steroids on iopamidol blood-brain transfer constant and plasma volume in brain tumors measured with X-ray computed tomography

SummaryTumor blood-brain transfer constant of iopamidol (K) and plasma volume (Vp) were measured in 10 patients with primary brain tumors before and after 7 days of dexamethasone treatment (4 × 4 mg per oral per day) using X-ray computed tomography. Both K and Vp decreased significantly after dexamethasone treatment with p < 0.01 and 0.09 respectively according to one-tail paired t-test. The mean percentage decrease in K and Vp was 32% and 10% respectively. Functional images of the two parameters before and after treatment were generated and showed clearly the effect of steroids on the reduction of K in brain tumors. In contrast, when before and after treatment contrast enhanced CT scans were compared, no difference was observed in the enhancement in 8 out of 10 cases. The result obtained support the conclusion that: (1) corticosteroids reduce the blood-brain permeability to small hydrophillic molecules; (2) the X-ray computed tomography method we have developed can be used to measure the K and Vp response of brain tumors to steroid therapy; and, (3) ordinary contrast enhanced CT scans at one fixed time or multiple times after contrast injection are not sensitive in detecting the reduction of K due to steroids.

The detection of loose bodies in the elbow: THE VALUE OF MRI AND CT ARTHROGRAPHY

Our aim was to determine the clinical value of MRI and CT arthrography in predicting the presence of loose bodies in the elbow. A series of 26 patients with mechanical symptoms in the elbow had plain radiography, MRI and CT arthrography, followed by routine arthroscopy of the elbow. The location and number of loose bodies determined by MRI and CT arthrography were recorded. Pre-operative plain radiography, MRI and CT arthrography were compared with arthroscopy. Both MRI and CT arthrography had excellent sensitivity (92% to 100%) but low to moderate specificity (15% to 77%) in identifying posteriorly-based loose bodies. Neither MRI nor CT arthrography was consistently sensitive (46% to 91%) or specific (13% to 73%) in predicting the presence or absence of loose bodies anteriorly. The overall sensitivity for the detection of loose bodies in either compartment was 88% to 100% and the specificity 20% to 70%. Pre-operative radiography had a similar sensitivity and specificity of 84% and 71%, respectively. Our results suggest that neither CT arthrography nor MRI is reliable or accurate enough to be any more effective than plain radiography alone in patients presenting with mechanical symptoms in the elbow.

Treatment of caliceal diverticular stones: transdiverticular percutaneous nephrolithotomy with creation of a neoinfundibulum.

PURPOSE To evaluate transdiverticular percutaneous nephrolithotomy (TDPN) with creation of a neoinfundibulum in the treatment of caliceal diverticular stones. PATIENTS AND METHODS Between 1990 and 1998, 18 patients with symptomatic calculi in caliceal diverticula underwent TDPN. Transdiverticular puncture into the renal collecting system with creation of a neoinfundibulum was used, eliminating the need for prolonged probing with a wire for the neck of the diverticulum. Eight diverticula were upper polar, six were interpolar, and four were in the lower pole. Stones were endoscopically treated with use of Lithoclast (Electromedical Systems, Lausanne, Switzerland), graspers, ultrasound, or a combination of these methods. RESULTS Sixteen kidneys (89%) were rendered stone-free at discharge. Two kidneys (11%) were left with stone fragments of 5 mm or smaller. Hospital stay ranged from 3 to 15 days (average, 7 days). Procedure time ranged from 45 to 169 minutes (average, 87 minutes). One patient developed a left renal-pleural fistula, which closed 1 week after chest tube drainage. No other complications were encountered for an overall complication rate of 6%. CONCLUSION TDPN is a safe and effective method for treating caliceal diverticular stones, with a complication rate comparable to other methods.

PERCUTANEOUS NEPHROLITHOTOMY OF A PELVIC KIDNEY: A POSTERIOR APPROACH THROUGH THE GREATER SCIATIC FORAMEN

Urolithiasis in a pelvic kidney can pose a management challenge to the urologist. We report on a patient with a symptomatic stone in a pelvic kidney managed by percutaneous nephrolithotomy through a posterior approach via the greater sciatic foramen. CASE REPORT

An absorptiometry method for the determination of arterial blood concentration of injected iodinated contrast agent

A single photon absorptiometry method to measure the arterial concentration of injected iodinated contrast agent was developed. A prototype absorptiometry unit was built which consists of either a square or circular cross section acrylic (polymethylmethacrylate) cuvette connected to an arterial catheter at one end and a paristaltic pump at the other via PE60 surgical tubing. At opposing ends of the length of the cuvette were a 0.4 GBq 125I source and a scintillation crystal/photomultiplier tube assembly. This assembly was connected to a single-channel analyser (SCA)/scaler unit to count the transmitted photons through the cuvette. The scaler was interfaced to an IBM PC and counts accumulated in preset time intervals were transmitted to the computer via a serial interface. Experiments were performed to calibrate the unit for measurement of blood concentration of contrast agent (Isovue 300) and to determine the dispersion characteristics of the unit. Deconvolution was used to correct the measured concentration waveform for the dispersion introduced by passage through the lead-in tubing and the cuvette. The precision of concentration measurements was determined to be between 5 and 10% using computer simulations and theoretical calculations. The method was used successfully in a number of patient and animal studies to measure the contrast concentration in blood following intravenous injection of contrast agent.

Abnormalities of the Hook of the Hamate in Patients with Carpal Tunnel Syndrome

The hook of the hamate is an important landmark in endoscopic carpal tunnel release. We studied the incidence of abnormalities of the hook of the hamate in patients with carpal tunnel syndrome. One hundred thirty-one consecutive patients presenting with carpal tunnel syndrome underwent carpal tunnel radiography. Abnormalities of the hook of the hamate were present in 6 of 131 patients (4.6%). The hook of the hamate was aplastic in 3 of 131 patients (2.3%). A bipartite hook of the hamate was present in 1 patient (0.8%). A nonunion of an old fracture of the hook of the hamate was found in two patients (1.6%). The previously reported incidence of an aplastic hook of the hamate in the general population is 1 of 1,452 (0.06%). The odds ratio revealed a 34-fold increase in the risk of hamate abnormalities in the carpal tunnel population (p<0.001). Hook of the hamate abnormalities may be more common than previously reported.

Intraarticular radial head osteotomy.

M alunron is a common sequela of nonoperative treatment of radial head fracture.‘,‘0 Although the majority of patients with malunited radial head fracture are asymptomatic, the condition can result in significant pain and motion loss because of incongruity of the joint surface. Reconstruction of malunited, intraarticular fractures has been useful in the restoration of satisfactory function in many joints@J,9,‘2 In this report we present a case of symptomatic malunited radial head fracture treated by intraarticular osteotomy.