Tibial tuberosity-trochlear groove distance in Chinese patients with or without recurrent patellar dislocation.

PURPOSE: To compare the tibial tuberosity-trochlear groove (TTTG) distance in Chinese patients with or without recurrent patellar dislocation. METHODS: The TTTG distance of 14 knees in 5 men and 9 women aged 16 to 38 years with recurrent patellar dislocation were compared with that of 73 control knees using magnetic resonance imaging. RESULTS: The mean TTTG distance was significantly greater in patients with recurrent patellar dislocation than in controls (16.4 mm vs. 10.1 mm, p<0.001). Six (43%) knees with recurrent patellar dislocation had the TTTG distance greater than the cut-off threshold of 16.4 mm, compared to none in controls. CONCLUSION: The TTTG distance is related to height and is shorter in Chinese than Caucasian patients; the threshold for tibial tuberosity transfer should be lower in Chinese patients.

Lower limb alignment in anterior cruciate ligament-deficient versus -intact knees.

PURPOSE: To compare anatomic lower limb features of anterior cruciate ligament (ACL)-deficient versus -intact knees in Chinese subjects. METHODS: Anatomic lower limb features (mechanical axis, tibiofemoral angle, posterior tibial slope, notch width index, and hip neck-shaft angle) of 25 men and 3 women aged 18 to 39 (mean, 26) years with ACL-deficient knees, and 16 men and 4 women aged 24 to 31 (mean, 28) years with ACL-intact knees were compared using radiography. RESULTS: The notch width index (0.26 vs. 0.29, p=0.02) was significantly smaller in ACL-deficient than ACL-intact knees. CONCLUSION: Small notch width was associated with a thin ACL and can be regarded as an anatomic intrinsic risk factor for ACL injuries.

Femoral tunnel widening after quadrupled hamstring anterior cruciate ligament reconstruction.

PURPOSE: To evaluate the extent of femoral tunnel widening after quadrupled hamstring anterior cruciate ligament reconstruction using femoral cross pin fixation in contrast to bioabsorbable screw fixation augmented with Endopearl. METHODS: 16 patients underwent cross pin femoral fixation and the next 15 underwent bioabsorbable screw fixation augmented with Endopearl. The patients were evaluated radiographically for femoral tunnel widening. Standard posteroanterior radiographs of the knee in full extension were taken at postoperative year 2 and 5. The tunnel width was measured at the opening, the widest and the most proximal parts of the femoral tunnel. RESULTS: In the femoral cross pin and bioabsorbable screw fixations, the mean femoral tunnel sizes were 7.6 and 8.0 mm, respectively. The overall mean tunnel widening at all measured sites were 2.7 and 1.8 mm at the 2-year follow-up and were 2.5 and 1.8 mm at the 5-year follow-up, respectively. The femoral tunnel widening was greater in the cross pin than the bioabsorbable screw group, but only the difference in the most proximal part was significant (p=0.01 at year 2 and p<0.001 at year 5). CONCLUSION: Femoral tunnel widening was greater in femoral cross pin fixation, probably related to the windshield-wiper and bungee-cord effects. It usually occurred in the first 2 years after the operation and remained static thereafter.

Anatomic variations of neurovascular structures of the ankle in relation to arthroscopic portals: a cadaveric study of Chinese subjects.

PURPOSE: To investigate anatomic variations of neurovascular structures in the ankle and the safety margin for arthroscopic portals. METHODS: 11 left and 12 right ankles from 8 female and 15 male fresh cadavers of Chinese ethnicity aged 53 to 88 (mean, 68) years were used. The ankle was standardised in a plantigrade position, zero-degree inversion, and neutral rotation. Four ankle portals, namely anteromedial (AM), anterolateral (AL), posteromedial (PM) and posterolateral (PL), were identified using 23-gauge needles. Skin and subcutaneous fat were dissected from the underlying fascia to visualise neurovascular structures. Distances were measured from: (1) the AM portal to the saphenous vein and nerve and its branches, (2) the AL portal to branches of the superficial peroneal nerves, of which the lateral one was labelled as the intermediate dorsal cutaneous branch and the medial one as the medial dorsal cutaneous branch, (3) the PM portal to the posterior tibial neurovascular bundles, and (4) the PL portal to the sural nerve. RESULTS: The distances from (1) the AM portal to branches of the great saphenous vein and nerve, and (2) the AL portal to the intermediate dorsal cutaneous branch of the superficial peroneal nerve were short and may be an anatomic hazard. Variations were significant among the cadavers in terms of distances of the portals to the neurovascular structures. CONCLUSION: In Chinese cadavers, variations of neurovascular structures are significant. Care must be taken to avoid inadvertent injury during ankle arthroscopy.

Pick-up test: an indication for opponensplasty in patients with severe carpal tunnel syndrome.

PURPOSE: To use a pick-up test to assess thenar motor deficit and results of opponensplasty. METHODS: Eight consecutive patients with idiopathic severe carpal tunnel syndrome and severe thenar motor deficit were identified. All were females aged 39 to 60 (mean, 53) years and right-hand dominant. The severity of thenar motor deficit was assessed using the pick-up test. Failure to pick up a coin with the thumb and index finger only in a normal pulp-to-pulp pincer grip was an indication for an opponensplasty (in addition to open carpal tunnel release) to hasten recovery of thumb abduction. Treatment outcome was assessed using the pick-up test at 6, 8, and 12 weeks. RESULTS: Preoperatively, all patients were unable to perform the pick-up test. At postoperative 6 weeks, all patients could pick up the coin with no difficulty and were satisfied with the result of opponensplasty. There was no relapse at subsequent follow-ups and no donor-site morbidity in terms of cosmesis, scar pain or infection. Grip strength and the range of wrist motion were 63% and 92% of the normal side, respectively. CONCLUSION: The pick-up test is a simple and reliable means of identifying those in need of an opponensplasty.

Rotary subluxation of the metacarpophalangeal thumb joint: a case report.

Irreducible rotary subluxation of the metacarpophalangeal joint (MCPJ) of the thumb is a rare entity. Open reduction is indicated when signs of irreducibility are seen on the radiographs. We present one such case caused by displacement of the sesamoid bone into the intercondylar notch of the first metacarpal bone. A 35-year-old woman sustained a twisting injury to her right thumb by pronating and hyperextending it while attempting to retrieve things that she had dropped into a basin conduit. True lateral radiographs showed rotary subluxation of the thumb MCPJ, a sesamoid bone overlapping with the metacarpal head, and loss of the subsesamoid joint space and an incongruent MCPJ on full flexion. A high level of clinical suspicion is needed to diagnose this rare entity.

Coherent multiscale image processing using dual-tree quaternion wavelets.

The dual-tree quaternion wavelet transform (QWT) is a new multiscale analysis tool for geometric image features. The QWT is a near shift-invariant tight frame representation whose coefficients sport a magnitude and three phases: two phases encode local image shifts while the third contains image texture information. The QWT is based on an alternative theory for the 2-D Hilbert transform and can be computed using a dual-tree filter bank with linear computational complexity. To demonstrate the properties of the QWT's coherent magnitude/phase representation, we develop an efficient and accurate procedure for estimating the local geometrical structure of an image. We also develop a new multiscale algorithm for estimating the disparity between a pair of images that is promising for image registration and flow estimation applications. The algorithm features multiscale phase unwrapping, linear complexity, and sub-pixel estimation accuracy.

Terahertz imaging with compressed sensing and phase retrieval.

We describe a novel, high-speed pulsed terahertz (THz) Fourier imaging system based on compressed sensing (CS), a new signal processing theory, which allows image reconstruction with fewer samples than traditionally required. Using CS, we successfully reconstruct a 64 x 64 image of an object with pixel size 1.4 mm using a randomly chosen subset of the 4096 pixels, which defines the image in the Fourier plane, and observe improved reconstruction quality when we apply phase correction. For our chosen image, only about 12% of the pixels are required for reassembling the image. In combination with phase retrieval, our system has the capability to reconstruct images with only a small subset of Fourier amplitude measurements and thus has potential application in THz imaging with cw sources.