Unifying model of carpal mechanics based on computationally derived isometric constraints and rules-based motion - the stable central column theory.

This study was part of a larger project to develop a (kinetic) theory of carpal motion based on computationally derived isometric constraints. Three-dimensional models were created from computed tomography scans of the wrists of ten normal subjects and carpal spatial relationships at physiological motion extremes were assessed. Specific points on the surface of the various carpal bones and the radius that remained isometric through range of movement were identified. Analysis of the isometric constraints and intercarpal motion suggests that the carpus functions as a stable central column (lunate-capitate-hamate-trapezoid-trapezium) with a supporting lateral column (scaphoid), which behaves as a 'two gear four bar linkage'. The triquetrum functions as an ulnar translation restraint, as well as controlling lunate flexion. The 'trapezoid'-shaped trapezoid places the trapezium anterior to the transverse plane of the radius and ulna, and thus rotates the principal axis of the central column to correspond to that used in the 'dart thrower's motion'. This study presents a forward kinematic analysis of the carpus that provides the basis for the development of a unifying kinetic theory of wrist motion based on isometric constraints and rules-based motion.

Active mobilisation following single cross grasp four-strand flexor tenorrhaphy (Adelaide repair).

This paper presents our initial experience using a single cross grasp, four-strand repair with an active mobilization regimen in a general trauma hospital setting. Variably experienced members of the trauma service of a large general hospital used a four-strand single cross grasp tenorrhaphy technique for acute repair of 73 zone one and two flexor digitorum profundus tendon lacerations in 53 patients. Postoperatively, all patients commenced an active mobilization program within 12 hours of the surgical repair. With a minimum 3 months post-repair follow-up of 89% of the repaired flexor digitorum profundus tendons, 71% of fingers achieved a good or excellent outcome. There were three (4.6%) flexor digitorum profundus ruptures post surgery. A four-strand single cross grasp repair using 3-0 braided polyester suture and active post-repair mobilization can achieve satisfactory outcomes in the general trauma service setting; however, patient compliance remains a problem.

Flexor tenorrhaphy tensile strength: reduction by cyclic loading: in vitro and ex vivo porcine study.

The integrity of the repair is critical to maintain coaptation of the severed flexor tendon end until healing has advanced sufficiently. In our hospital, we use a modified Savage repair (four-strand Adelaide technique) using 3-0 Ethibond (Ethicon, Somerville, NJ, USA) for acute flexor tenorrhaphy and an active postrepair mobilization protocol. To explain the apparent differences between the theoretical and actual repair strength of a multistrand repair in a single tension test and the reduced strength of a repair subjected to cyclic loading, we compared single and cyclical tensile loading with different suture in vitro configurations of 3-0 Ethibond (Ethicon, Somerville, NJ, USA; one, two, and four strands) and an ex vivo four-strand repair of freshly divided porcine tendon to calculate the ultimate tensile strength (UTS). Mechanical testing was repeated 15 times with both single tensile and cyclical loading for each suture configuration and porcine repair. In the in vitro model, the presence of a knot in a single strand reduced the UTS by 50%. The stiffness of a knotted strand was substantially less than the unknotted strand but became identical after cyclical loading. There was no statistical significance of the UTS between single and cyclical loading with different numbers of strands in this model. In the ex vivo four-strand porcine repair model, there was a significant reduction in UTS with cyclical loading, which equated to the number of strands times the strength of the knotted strand. This discrepancy can be explained by the change in stiffness of the knotted strand after cyclical loading and has important implications for previous studies of suture tendon repair using single tensile loading where the UTS may have been overestimated. We believe that cyclical loading is more representative of physiological loading after acute flexor tendon repair and should be the testing model of choice in suture tenorrhaphy studies.

A multivariate statistical analysis of surface water chemistry data--the Ankobra Basin, Ghana.

R-mode hierarchical cluster and principal component analysis (PCA) were simultaneously applied to surface water hydrochemical data from three different locations, Ankwaso, Dominase and Prestea, along the Ankobra Basin, Ghana, to extract principal factors corresponding to the different sources of variation in the hydrochemistry, with the objective of defining the main controls on the hydrochemistry at the basin scale. Using the Kaiser criterion, principal components (PC) were extracted from the data and rotated using varimax normalization, for each location. The varimax rotation ensured that variation in the data was maximized for easy interpretation of the results. The analysis reduced 30, 33 and 33 data points, respectively, for Ankwaso, Dominase and Prestea to four, three and four PC representing the sources of variation in the hydrochemistry at the three different locations. Though the PC analysis proved to be more robust at unveiling the sources of variation in the hydrochemistry than the R-mode hierarchical cluster analysis (HCA), the combined use of both techniques resulted in more reliable interpretations of the hydrochemistry. On the basis of these analyses, the hydrochemistry of the basin is controlled largely by the weathering of minerals (silicates, carbonates, gypsum and apatite) from the underlying meta-sediments of the Birimian and Tarkwaian Systems, and the decay of organic matter from the heavily forested regions. Concentrations of the major chemical parameters are within naturally acceptable limits and do not pose threats to the local ecology and humans. There is no strong evidence of high anthropogenic impacts on the major anions and cations used for this research, though there are variations at the different locations studied. The hydrochemistry at Ankwaso is principally controlled by the weathering of silicate minerals, whereas those of Dominase and Prestea are, respectively, influenced by precipitation and domestic wastewaters, and the decay of organic matter.

Migration of the Duraloc cup at two years.

We carried out 71 primary total hip arthroplasties using porous-coated, hemispherical press-fit Duraloc '100 Series' cups in 68 consecutive patients; 61 were combined with the cementless Spotorno stem and ten with the cemented Lubinus SP II stem. Under-reaming of 2 mm achieved a press-fit. Of the 71 hips, 69 (97.1%) were followed up after a mean of 2.4 years. Migration analysis was performed by the Ein Bild Rontgen Analyse method, with an accuracy of 1 mm. The mean total migration after 24 months was 1.13 mm. Using the definition of loosening as a total migration of 1 mm, it follows that 30 out of 63 cups (48%) were loose at 24 months.

Suprascapular nerve rotator cuff compression syndrome in volleyball players.

Selective denervation of the infraspinatus muscle producing weakness and wasting has been reported in certain sports (eg, volleyball and baseball). Nerve kinking or friction caused by excessive infraspinatus motion and compression by superior or inferior transverse scapular ligament or ganglions have been proposed as possible causes. However, in extreme abduction with full external rotation of the shoulder, the medial tendinous margin between the infraspinatus and supraspinatus muscles impinges strongly against the lateral edge of scapular spine, compressing the intervening infraspinatus branch of the suprascapular nerve. Spinaglenoid notchplasty has been performed in 5 elite volleyball players with infraspinatus neuropathy, allowing recovery of shoulder function in all patients and correction of infraspinatus muscle wasting. All returned to the same or higher level of volleyball by 8 months after surgery. An alternative cause of infraspinatus compromise in volleyball players is proposed and has been treated surgically with satisfactory outcome.

Proximal scaphoid costo-osteochondral replacement arthroplasty.

Deficiency of the proximal pole of the scaphoid due to fracture or necrosis was treated by costo-osteochondral replacement arthroplasty using rib bone/cartilage autografts in 22 patients who were followed prospectively and assessed at a median 24 month follow-up (range, 12-72 months). Improvement of wrist function occurred in all patients with increased motion, improved grip strength and less pain. The average modified Green and O'Brien Wrist Function Score improved from 53 out of 100 preoperatively to 80 at the most recent review. All patients were graded fair or poor at initial review and all but three improved to good or excellent at the most recent assessment. Despite the absence of the scapholunate ligament, carpal alignment did not deteriorate in any patient and there were no graft non-unions or significant complications. In the short and medium term a costo-osteochondral autograft can satisfactorily restore mechanical integrity of the scaphoid proximal pole and maintain wrist motion while avoiding the potential complications of alternative replacement arthroplasty techniques.

Natural history of anterior knee pain: a 14- to 20-year follow-up of nonoperative management.

We describe a consecutive series of girls with idiopathic anterior knee pain in adolescence and who were treated nonoperatively. At a mean follow-up of 16 years, 22% had no pain, 71% thought that their symptoms were better than at presentation, 88% used analgesics rarely or not at all, and 90% continued to participate regularly in sports. Nevertheless, about one in four of the patients continued to have significant symptoms for < or = 20 years after presentation. No features were identified that predicted those patients in whom symptoms would persist. We conclude that surgical treatment of idiopathic anterior knee pain in adolescents is not justified until a procedure has been shown to provide a better outcome than that reported here or until a way has been found to distinguish the few patients who will not get better spontaneously from the majority who will.

A further tendon retrieval trick.

Atraumatic delivery of the retracted flexor tendon ends following laceration is crucial for accurate tenorrhaphy. Sourmelis and McGrouther (1987) developed a useful method of delivering the proximal flexor tendon and a modification is presented here which further aids atraumatic tenorrhaphy.

Treatment of humeral shaft fractures with the Seidel intramedullary nail.

BACKGROUND: The use of intremedullary nails for the management of humeral shaft fractures has been controversial. Recently, the Seidel nail has become available. The purpose of this study was to review our initial experience with the Seidel nail. METHODS: A retrospective clinical and radiographic review of 25 consecutive patients treated with Seidel intramedullary humeral nail was performed. The nail was used for non-union in 10 patients, delayed union in four, acute fracture in eight and pathological fracture in three. Eighteen of the 19 survivors were clinically reviewed at an average of 15 months (range 8-15). Pain, function, satisfaction, shoulder power, range of motion and clinical outcome were graded using the UCLA shoulder score. RESULTS: Pain was present at the shoulder in four patients and at the fracture site in nine. Average shoulder abduction was 99 degrees and nine patients could not abduct the shoulder past 90 degrees. Sixty-six percent of patients reviewed were graded as only fair or poor using the UCLA shoulder score. In three patients rotational control was not achieved with the distal locking device at the time of surgery. Complications included non-union in 10 patients and three intra-operative fractures. CONCLUSIONS: Non-union was more likely to occur if rotational control was not obtained, or if the patient had the nail inserted for a previous non-union. Use of the Seidel nail frequently leads to shoulder pain and dysfunction. The distal locking device is unreliable and predisposes to non-union. We do not recommend the continued use of the Seidel nail.

Results of interfascicular nerve grafting for radial nerve lesions.

During the 10 year interval 1979-1989, 20 patients underwent nerve grafting of a radial nerve lesion, 13 high radial and 7 posterior interosseous. Average follow-up was 38 months (range 12 months-10 years). Overall 72% of patients achieved a Highet Scale rating of M3 or better function and 44% M4 or better recovery. Age of the patient and length of the nerve graft did not seem to influence outcome. Time from initial injury to nerve grafting did affect outcome, with 85% of patients grafted within 6 months obtaining M3 or better recovery. No patient grafted 12 months after injury recovered any useful function. Lesions of the posterior interosseous nerve had a consistently superior recovery. Power grip strength in the affected hand of patients averaged 60% of the unaffected hand while key pinch averaged 74%. There was good correlation between the Highet Scale rating of recovery and the ultimate power grip or key pinch strength obtained. Hand dexterity, as assessed by the turning and displacing tests of the Minnesota Rate of Manipulation Test, displayed a wide range of scores in both affected and unaffected hands. Nevertheless, a relative score derived from the results obtained in the displacing test did show correlation with the Highet Scale rating. All patients with M4 or better recovery obtained relative scores for the affected hand that were in the middle of the range of scores considered an average performance for a normal population. Patients who achieved M4 or better nerve recovery following radial nerve grafting also obtained a functional hand as evidenced by the results of grip, key pinch strength, and hand dexterity testing. Lesser degrees of recovery were accompanied by poorer strength and dexterity ratings reflecting inferior function.

Posterior shoulder dislocation and humeral head necrosis in a recreational scuba diver with diabetes.

An insulin-dependent diabetic who was previously a recreational scuba diver suffered a posterior shoulder dislocation after a trivial injury and was subsequently found to have local necrosis of the humeral head. The only definite conclusion that can be reached is that this patient should not dive again.

Intercarpal arthrodesis by dowel bone grafting.

Successful intercarpal arthrodesis requires a stable fusion with maintenance of correct alignment and spatial relationship of the carpus. The technique described utilizes a series of tube saws to fashion the arthrodesis bed and then insert a sized iliac crest dowel bone graft with a tight interference fit. This technique has been used in 24 patients over a two-year period in both medial and lateral column intercarpal fusions. All wrists had fused by the tenth post-operative month. The technique is precise, reproducible and technically simple with a high fusion rate and minimal donor site morbidity.

A modified halo frame to assist omentum transfer to the scalp.

A modification of the halo frame to facilitate management of major scalp wounds is described. It has been used successfully in the management of a major scalp defect covered by a microvascular omental free flap. It has potential application in managing a replanted scalp.

The natural history of anterior knee pain in adolescents.

Anterior knee pain in adolescents is generally recognised as a common but benign self-limiting condition. Although many operative procedures for its treatment have been proposed, there is little statistical evidence that they are more effective than expectant management. A group of 54 adolescent girls has been followed for two to eight years from presentation with anterior knee pain. Although some pain persisted in the majority, in many the symptoms declined in severity. This study provides a baseline for comparison with the results of operative intervention; it is suggested that surgical treatment is unproven and unnecessary.

A simple two-handed surgeon's knot.

The technique described allows the surgeon to perform a quick, secure, controlled double primary throw when tying the standard surgeon's knot, further enhancing the advantages of hand tying.