Biomedical subjects
M P Hahn
Publications and source records attributed to M P Hahn.
[Pediatric forearm fractures. Diagnosis, therapy and possible complications].
Nonoperative management of forearm fractures in children has a good outcome in over 90% of all cases. In our own series (n = 102) there were only six children (6.1%) with significant limitation (> 25 degrees) of forearm rotation. In these cases two out of four (50%) were located in the proximal third but only two out of 68 in the distal third. Indications for operative stabilization are the following: compound fractures, fractures associated with vessel and nerve injuries, joint fractures, dislocated fractures of the middle and proximal third, and Monteggia/Galeazzi injuries. As implants intramedullary devices are preferred. Twenty children were managed with elastic IM rods between 1994 and 1995 at our institution. At final follow-up all had a free ROM and a maximal axial malalignment of less than 5 degrees. In the region of the distal forearm K-wires are useful. Plates play a dominant role for corrections and nonunions; external skeletal stabilization is indicated for temporary fixation in compound fractures.
[Distal tibial fracture--an indication for osteosynthesis with the unreamed intramedullary nail?].
In a prospective study, 50 fractures of the distal fifth of the tibia with additional involvement of the ankle joint in 18 patients were stabilized by unreamed nailing. In all, 90% of all fractures healed uneventfully without further surgical intervention after unreamed nailing, the highest ratio of complications (22%) being seen in all patients with distal fractures of the fibula without additional plating (of the fibula). Tibial fractures close to the ankle joint can be managed by unreamed nailing; distal fractures of the fibula should be additionally stabilized by fibular plating.
[Retrograde interlocking nailing of distal femoral fractures with the intramedullary supracondylar nail].
Between June 1993 and September 1995, 18 distal femoral fractures were treated using the supracondylar intramedullary nail. There were 8 type A fractures and 10 type C fractures (AO classification). The operative technique involved retrograde insertion of an unreamed supracondylar nail through the intercondylar notch. Follow-up was available on all patients and averaged 18.3 months (range 6-32 months). All fractures healed with an average time to union of 12.4 weeks (range 8-16 weeks). Bone grafting was not necessary in any case. Sixteen patients achieved almost the same ROM as they had had before the injury. One patient developed a varus malignant and underwent correction with a supracondylar osteotomy 20 months post trauma. There were no infections or nonunions. The retrograde supracondylar nail is an excellent alternative to plate osteosynthesis in the management of dia- and supracondylar femoral fractures.
[Ultrasound follow-up of callus distraction of the tibia. Technique, possibilities and limits].
In a prospective study 20 patients were monitored with serial sonograms and radiographs during distraction osteogenesis at the lower limb. All sonograms were obtained in four planes using a 7.5 MHz transducer. The distraction gap was seen as a sonolucent area in all patients after corticotomy. At an average of 20.7 (14-28) days after the beginning of the distraction, echogenic foci occurred and showed increasing longitudinal alignment with further distraction. Radiographical signs of beginning mineralization were seen an average of 48.3 days after the start of the distraction. Exact measurement of the distraction gap was possible in all patients during lengthening. Bone healing complications and hematoma could be detected by ultrasound. A rapid increase of bone mineralization was seen after the distraction was stopped. With increasing cortication of the regenerate bone, sonograms showed a hyper-reflecting solid line so that further mineralization and the time of removal of the fixator could not be assessed by ultrasound. Ultrasound is more sensitive than radiography in identifying new bone formation during distraction, measuring the length of the distraction gap, and detecting early bone-healing complications and can therefore reduce the need for radiographs.
[Is functional conservative treatment of stable lateral ankle fractures justified?].
For Weber type B ankle fractures, operative treatment is generally recommended. Yet, there is no general agreement about the role of functional treatment. In a prospective follow-up study from December 1990 to May 1994, 146 patients were reviewed. The mean follow-up time was 17.3 months for clinical examinations and 19.6 months for X-rays. There were no failures. In all, 85 patients (58%) were treated conservatively (group K). A below-the-knee plaster was applied to 23 patients for 6 weeks, and 62 patients had functional treatment with an ankle brace. According to the Olerud Score, the first subgroup (K-plaster) achieved 89.4 points and the last (K-func.) reached 95.7 points. There were no signs of post-traumatic arthritis. 61 patients (42%) had open reduction and internal osteosynthesis (group OP). In 19 patients a plaster immobilization was necessary, and in 42 patients early mobilization was possible. The first subgroup (OP-plaster) achieved 85.0 points in the Olerud Score; the last (OP-func.) achieved 92.4 points. According to the degree of instability following ankle injuries, a new algorithm for treatment of type B ankle fractures is described, emphasizing early mobilization and functional after treatment.
[Pseudarthroses in childhood].
Nonunion of fractures in children is rare. It occurs after pathological fractures, post-infection and after incorrect osteosynthesis. Sometimes, delayed union of one bone in the forearm or the lower leg can be observed. Typical cases of nonunion are those of the radial condyle of the humerus and the femoral neck. A different problem is presented by congenital pseudoarthroses. The treatments of choice for nonunion are autogenous bone grafting and external or internal skeletal stabilization. In the radial part of the elbow joint the only indication for operative correction is an irritation of the ulnar nerve (ventralization of the nerve and supracondylar osteotomy). Nonunion of the femoral neck can be avoided by internal screw fixation.
Vertical deceleration injuries: a comparative study of the injury patterns of 101 patients after accidental and intentional high falls.
We analysed the pattern of injury of 101 adult patients who were treated in our Trauma Center after a fall from an average height of 7.2 m between 1987 and 1990. In 62 patients the fall was accidental, and 39 jumped with suicidal intent. The most common injuries were fractures of the thoracic and lumbar spine (83.0 per cent) especially of the thoracolumbar junction. The pattern of limb injuries is towards a significant preference of the metaphyseal and epiphyseal parts of the bones of the distal joints (wrist, elbow, ankle, subtalar). Fractures of the diaphyseal areas and the proximal joints (shoulder, humerus, hip, femur) were rare. The incidence of thoracic (20.8 per cent) and pelvic injuries (30.0 per cent) was relatively lower. Blunt abdominal injury (5.9 per cent) was rare after a fall from a great height. Head injuries occurred in only 27 per cent of our patients who all survived their transport to hospital. There is no significant difference in injury patterns between deliberate and accidental falls, but there is a higher number of isolated injuries in all patients after unsuccessful suicidal jumps.
[Elastic intramedullary nailing--a concept for treatment of unstable forearm fractures in childhood].
The standard treatment for forearm fractures in children is usually conservative. Unstable fractures of the proximal parts of the forearm often show poor results after nonoperative management, so that these fractures require surgical intervention. We report about 20 children ranging in age from 6 to 14 years who were treated by elastic intramedullary nailing. Ten patients were treated by intramedullary pinning immediately after their accident; 10 required intramedullary nailing after failure of the conservative treatment and redislocations of their fractures. At the time of follow-up 6 months later, functional results were "excellent" in 16 children, "good" in 3 children and "fair" in one child. There were no serious complications apart from the occurrence of one delayed union. According to these results intramedullary nailing can be recommended for the treatment of unstable fractures of the proximal and middle parts of the forearm in children.
[Elbow arthrodesis and its alternative].
Significant functional impairment, increasing pain or joint infection are the indications for arthrodesis of the elbow joint. Six patients underwent a compression arthrodesis with internal and external fixation and an additional bone graft in our institution between 1987 and 1993. Out of this series only one patient developed a non-union due to a fall on the extremity. In a series of nine patients treated with external fixation alone between 1978 and 1987, four patients developed a non-union. Unlike other joints, there is no optimal position for arthrodesis of the elbow and the functional deficit cannot be compensated by the other joints of the upper extremity. Therefore, it should be useful to know if an interposition arthroplasty is possible. With this technique a joint infection can be healed. Ten patients treated with this technique between 1987 and 1993 had no recurrent infection. Two patients had instability. The best results were achieved in post-traumatic joint stiffness. Permanent instability and post-traumatic arthritis are indications for an allo-arthroplasty. Contraindications are a previous joint infection and intensive bone loss, as well as ipsilateral shoulder ankylosis and neuropathic joint disorders. In younger patients, resection arthroplasty is better due to a high loosening rate of the prostheses.
[Treatment concept and results of grade 3 open fractures with arterial injuries requiring reconstruction].
Ninety-one open fractures associated with arterial injury requiring vascular repair (type IIIC injuries) were treated at the University of Louisville between May 1983 and January 1994. Involved anatomical areas were the humerus (6x), the forearm (11x), the femur (16x), the tibia (36x), the ankle (11x) and the foot (11x). Fracture management consisted of meticulous radical debridement, copious wound irrigation, fasciotomy and fracture stabilization. Additionally, 49 wounds (53.8%) were treated with the supplemental local use of antibiotics (tobramycin-PMMA-beads). Thirty-four patients underwent primary amputation whereas 57 repairs of the injured vessels were performed. There were 7 secondary amputations due to infection or poor revascularization resulting in an overall amputation rate of 45.1%. The wound infection rate was 12.1% (11/91) and the rate for osteomyelitis was 3.3% (3/91). The local use of the antibiotic beads was of significant benefit to lower infectious complications. Primary coverage of the soft tissue defect with free tissue transfer was associated with a high infection rate (2/3) and is not recommended for this type of injury. Temporary wound coverage with the "antibiotic bead pouch" technique until wound closure can be obtained in a sterile and viable environment leads to more satisfying results.
[Ultrasound follow-up of callus distraction--an alternative to roentgen diagnosis?].
In a prospective study 20 patients were regularly monitored with sonograms in four planes and radiographs during distraction osteogenesis of the lower limb. Ultrasonography is more sensitive than radiography in identifying new bone formations during distraction, in measuring the length of the distraction gap, and in detecting early bone healing complications, and can therefore reduce the need for radiographs. Radiographs are necessary to assess the time of fixator removal and the axis of the leg.
[Treatment of supracondylar femoral fracture proximal to a knee joint endoprosthesis by retrograde interlocking nailing].
A case of a supracondylar femoral fracture proximal to a total knee prosthesis is reported. This difficult fracture was managed with retrograde intramedullary locked nailing. The time to union was 6 weeks. Cancellous bone grafting was not necessary. At final follow up the patient had a knee score of 90 and a functional score of 80 points. This was equal to the result after joint replacement prior to the injury.
[Biomechanical study of the initial stability of various arthrodesis methods for the upper ankle joint].
Arthrodesis of the ankle joint is commonly, performed to treat severe arthritis. Three different techniques have been biomechanically evaluated for initial stability: fusion with three isolated tibio-talar lag screws (type I), which was inaugurated by Wagner; a second fusion technique with two isolated tibio-talar lag screws and an anterior tibio-talar three-hole 3.5 mm AO compression plate (type II); and type-II fusion with an additional lag screw through the center hole of the anterior plate (type III). Ten fresh cadaver ankles were used for biomechanical evaluation. Bone stock quality was compared before fusion by CT scan and osteodensitometry. Osteopenic ankle joints (bone density less than 80% of the median density) were excluded. Each ankle fusion was stressed with 15 Nm in a universal testing machine (UTS 10, Ulm, Germany) in antero-posterior and medio-lateral directions and in a rotational torque technique. The movements at the fusion gap were recorded by computer-assisted image analysis. A video camera recorded the displacement of four active markers on both sides of the fusion line during loading in real time. A computer-assisted calculation of the dislocation at the fusion gap was performed. This technique provides comparable results except for systemic failure induced by the fixation device of the testing machine. The results revealed comparable initial stability with types I (0.063 mm/Nm) and III (0.074 mm/Nm; P = 0.95) ankle fusion. Type-II fusion was significantly less favorable concerning initial stability (0.14 mm/Nm; P < 0.01, Duncan's test for multiple comparisons). Our biomechanical results advertise isolated lag screws for ankle fusion.
[Classification, therapy and complications of pediatric femoral neck fractures].
Femoral neck fractures in children are rare injuries (less than 1 percent). The fracture pattern consists of transepiphyseal, transcervical, cervicotrochanteric and intertrochanteric fractures. Main problems with this type of injury are avascular necrosis, varus deformity, nonunion and premature epiphyseal closure. Varus and nonunion are affected by the treatment, vascular compromise with necrosis or growth problems are not related to therapy and hardly to control. Primary dislocated fractures are emergencies and need immediate operative management. Stabilization is achieved with K-wires or cancellous screws dependent on the child's age. In children below 3 years a pelvis cast is necessary post-operatively. Partial weight bearing is started 6 weeks post trauma and is rapidly increased to full weight bearing. One year post-operation the metal is removed, K-wires directly after bony healing.
[Surgical management of complications of open pelvic injuries].
Open pelvic fractures are rare fractures usually resulting from a severe trauma. Only 4 of 121 patients treated operatively in 1994 for a pelvic trauma showed an open injury. The high lethality is caused by two complications: in the early phase the patient is threatened by bleeding to death and in the following course sepsis determines the lethal outcome. Only an aggressive surgical management prevents or treats such complications. The presented concept comprises in the end the hemipelvectomy and an intensive care management for prophylaxis of septic complications. So the lethality was diminished.
[Injury pattern after fall from great height. An analysis of 101 cases].
There are few references discussing the typical injury patterns of adults after a fall from a height. We present the pattern of injury in 101 adult patients who were treated between 1987 and 1990 at our trauma center after falling from an average height of 7.2 m. In 62 patients the fall was accidental; 39 patients tried to commit suicide by jumping from a height. The most common injuries were fractures of the thoracic and lumbar spine (83.0%) with a preference for the thoracolumbar junction. Fracture of the lower limbs occurred in 45%. The most frequent injuries were fractures of the os calcis (64.4%) and the ankle joint (26.6%). Twenty-five percent of all patients suffered from fractures in the upper limbs with a preference for the distal radius (56.6%) and the elbow (44.0%). There were no differences between the injury patterns after a fall from a height of more than 7 m or less than 7 m. The incidence of thoracic and pelvic injuries (30.0%) increased after falls from more than 7 m. The neurological complications of injuries to the spine corresponded to increasing height. According to our analysis blunt abdominal trauma is an uncommon injury after falling from a great height. Head injuries, which would be expected to be the most common cause of death in all non-survivors in the literature, only occurred in 27% of our patients who all survived their transport to hospital.
[Isolated talus metastasis of an occult bronchial carcinoma--a rare cause for chronic foot disorders].
A case of a solitary metastatic lesion of the talus from an occult histologically confirmed bronchogenic carcinoma is reported. Clinical, radiologic, histological, and laboratory manifestations are described. Four months after complete resection of the talus and consecutive internal and external fixation of the ankle joint a below-knee amputation was done because of progressive infiltration. A review is given on reports in the literature of rare cases of solitary metastatic deposits of malignant tumors below knee and elbow. This unusual cause of foot pain should be taken into account concerning differential diagnosis in elderly patients. A mistake for a septic osteolysis is possible.