Prospective comparison of retrograde and antegrade femoral intramedullary nailing.

OBJECTIVE: To prospectively compare the results, function, and complications of antegrade and retrograde femoral nailing for femoral shaft fractures. DESIGN: Prospective, randomized. SETTING: Urban Level 1 trauma center. PATIENTS: One hundred consecutive femoral shaft fractures. Fifty-four nails inserted retrograde and forty-six inserted antegrade. INTERVENTION: Ten-millimeter antegrade or retrograde nail inserted for a femoral shaft fracture after reaming. OUTCOME MEASUREMENTS: A comparison of the outcomes after antegrade and retrograde nailing of the femur. Data were collected for analysis on comminution, set-up and starting point times, open grade, location of fracture, injury severity score, body mass index, time to union, knee pain and motion, hip and thigh pain, and nail to intramedullary canal diameter difference. A linear regression model was employed. RESULTS: Knee motion was 120 degrees in all but one knee in each group. The antegrade nailed femurs healed faster than those treated retrograde (A = 14.4, R = 18.1 weeks, p = 0.0496). More patients required dynamization for union in the retrograde insertion group (17 percent versus 5 percent, p = 0.10, NS). In a linear regression model, a nail-to-canal-diameter difference and retrograde nailing had an association with an increased time to union. Knee pain was equal in both groups; however, thigh pain was higher in the antegrade group (p = 0.0108). All of the antegrade nailed femurs healed (100 percent), and 98 percent (one nonunion) of the retrograde femurs healed after secondary procedures. CONCLUSIONS: Both antegrade and retrograde nailing yielded high union rates. Each insertion technique has its own advantages and disadvantages. The two insertion modes appear to be relatively equal for the treatment of femoral shaft fractures.

Effects of retrograde femoral intramedullary nailing on the patellofemoral articulation.

OBJECTIVE: To determine the patellofemoral contact areas as well as mean and maximal pressures after retrograde intramedullary nailing in a cadaveric model. STUDY DESIGN: Pressure-sensitive film was used to analyze patellofemoral joint pressures after insertion of a retrograde femoral nail in a cadaveric specimen. METHODS: A retrograde femoral nail was inserted into seven cadaveric knees. Pressure-sensitive film was placed into the patellofemoral joint and physiologic loads (700 newtons) were applied to the knee joint at 90 degrees and 120 degrees of flexion. Testing was performed with the nail three millimeters deep to the cartilage (In), flush with the cartilage (Flush), and one millimeter prominent (Out). The intact knee served as the Control. RESULTS: The mean contact areas showed no statistical differences among the four groups. There was a significant increase in mean pressure at 120 degrees and maximum pressure at 90 degrees and 120 degrees for the Out group when compared with the Control, In, and Flush groups (p < 0.001). CONCLUSIONS: There were no significant differences in mean contact pressure, contact area, or maximum pressure among the Control, three-millimeter insertion depth, or flush insertion groups. There was, however, a significant increase in mean and maximum pressures with the nail one millimeter prominent. These results indicate that placement of a retrograde femoral intramedullary nail is critical, but that proper placement should not significantly influence the biomechanics of the patellofemoral joint.

Retrograde intramedullary nailing of femoral diaphyseal fractures.

OBJECTIVES: To prospectively evaluate the results of retrograde intramedullary nailing of femoral shaft fractures. DESIGN: Prospective, consecutive series. PATIENTS AND SETTING: All patients with a femoral shaft fracture admitted at an urban Level 1 trauma center from December 1995 to December 1996 were treated with a retrograde femoral intramedullary nail. INTERVENTION: Retrograde femoral intramedullary nailing was performed on a radiolucent operating room table. Through a three-centimeter medial parapatellar incision, a reamed ten-millimeter retrograde nail was inserted. METHODS: From the time of injury until union, the following parameters were assessed: operative time, blood loss, extent of comminution, open grade, associated injuries, Injury Severity Score, body mass index, time to union, secondary procedures, range of motion in the knee. and complications. RESULTS: Fifty-seven patients with sixty-one fractures were available for follow-up, which averaged 43.1 weeks. Fifty-two percent of fractures demonstrated Winquist Type 3 or 4 comminution. Twenty-six percent of the fractures were open. Fifty-two fractures healed after the initial nailing, five of seven dynamized nails healed, and one patient with bone loss requiring bone graft united yielding a final union rate of 95 percent. Of the three nonunions (5 percent), two healed with exchange nailing and one remains asymptomatic at seventy-one weeks. One patient developed a late septic knee that resolved with treatment. Excellent range of motion in the knee was obtained by those patients who did not have other ipsilateral limb injuries. CONCLUSIONS: This consecutive series had a 95 percent union rate after nailing and dynamization as necessary. No knee problems were associated with the retrograde femoral intramedullary nailing technique. The one septic knee raises concerns about the use of retrograde nailing in severe open femoral shaft fractures. Retrograde femoral nailing should be given serious consideration as an alternative to antegrade femoral nailing.

Indications and techniques for external fixation of the pelvis.

Pelvic ring disruption is often accompanied by severe, multiple injuries to the organs, vessels, and nerves within the true pelvis. Mortality in the acute resuscitative period is usually due to hemorrhage and hemodynamic instability. Establishing rapid, provisional pelvic stability with external fixation is of immediate importance in the hemodynamically unstable patient, because fixation contributes to hemostasis. Orthopaedic surgeons should anticipate the likelihood of hemorrhage in patients with pelvic ring disruption and should apply external fixation immediately to minimize morbidity and mortality.

Intramedullary nailing of femoral shaft fractures. Part III: Long-term effects of static interlocking fixation.

The results of treatment of fractures of the femoral shaft with static interlocking nailing were reviewed retrospectively to determine the clinical importance of any stress-riser or stress-shielding properties of the nail. These properties, if relevant, would have been manifested by refracture of the femur, either through a hole used for a locking screw or through the original site of fracture after extraction of the device. Two hundred and fourteen fractures that had been treated with static interlocking nailing and that had healed without conversion to dynamic intramedullary fixation were divided into two groups. In Group I, which comprised 111 fractures, the static interlocking-fixation device was retained and in Group II, which comprised 103 fractures, the static interlocking-fixation device was removed during one operative procedure at an average of fourteen months after the injury. The average duration of follow-up was thirty months from the time of the original fixation in both groups. All patients in Group II were followed for a minimum of six months after removal of the nail. No femur in Group I, in which the static interlocked nail remained in situ, refractured. No femur in either group fractured through the proximal or the distal holes used for the locking screws. No locking screws or nails broke. One patient (1 per cent) in Group II had a refracture of the femoral shaft through the site of the original fracture six weeks after removal of the nail.(ABSTRACT TRUNCATED AT 250 WORDS)

Interlocking intramedullary nailing for ipsilateral fractures of the femoral shaft and distal part of the femur.

A review of the data on 684 fractures of the femur that had been treated with intramedullary nailing led to the identification of twenty-three patients who had had a fracture of the shaft of the femur with an accompanying ipsilateral supracondylar fracture (twelve patients, group I) or a concomitant ipsilateral intercondylar fracture (eleven patients, group II). The group-I fractures had been treated with interlocking nailing without supplemental fixation. In group II, ten fractures were stabilized with interlocking nailing and supplemental screw fixation and one, with interlocking nailing and a supplemental plate and screws. The average time to union for all fractures was nineteen weeks (range, twelve to thirty-six weeks), and the average duration of clinical and radiographic follow-up was thirty months (range, nine to fifty-nine months). In group I, alignment of the femur was within 5 degrees of normal in ten of the twelve fractures. In group II, seven intra-articular fractures healed in anatomical alignment, three had slight articular displacement (1.0 to 3.0 millimeters), and one had displacement of more than 3.0 millimeters. The average range of motion of the knee at the most recent follow-up was 0 to 120 degrees in group I and 0 to 115 degrees in group II. Two patients (both in group II) needed a reoperation for a previously unrecognized fracture of a femoral condyle in the coronal plane; post-traumatic arthritis developed in both. No patient in either group had loss of fixation or failure of the implant. We concluded that ipsilateral diaphyseal, supracondylar, and intercondylar fractures of the femur can be adequately stabilized with interlocking nailing and supplemental intercondylar screw fixation. The presence of a fracture in the coronal plane of a femoral condyle (AO type-B3 and type-C3 injuries) is a relative contraindication to the use of this technique.

Complications of reamed intramedullary nailing of the tibia.

A retrospective review of 60 acute fractures of the tibia treated with reamed intramedullary nailing was undertaken to document the spectrum of complications associated with this procedure. Forty-five tibial fractures were followed to radiographic union; follow-up averaged 25 months (range, 10-63 months). Complications were categorized into intraoperative, early postoperative, and late postoperative groups. Intraoperative complications occurred in 6 of the 60 (10%) fractures and included propagation of the tibial fracture into the insertion site of the nail in four cases. In each of two other fractures, at least one of the proximal interlocking screws was documented to have poor bony purchase. These complications did not affect final fracture alignment or clinical result. Early complications included soft-tissue complications, complications of fixation, and neurologic complications. Four patients developed hematomas at the nail insertion site. Eight fractures were stabilized in greater than 5 degrees of varus or valgus. Neurologic deficits directly related to the procedure were documented in 18 patients (30%). The majority were minor sensory neuropraxias of the peroneal nerve. Sixteen (89%) of these nerve palsies were transient, resolving within 3-6 months. Two patients had persistent nerve deficits at 1-year follow-up. In the late complications group, 10 of the 45 (22%) tibial fractures followed to union developed patellar tendinitis. Nonunion developed in two fractures, both of which required additional surgical procedures to obtain fracture union. Two deep infections occurred, both of which resolved after local wound care, fracture union, and nail removal. Overall, 26 of the 45 tibial fractures available for follow-up (58%) developed some complication attributable to the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Heterotopic ossification about the hip after intramedullary nailing for fractures of the femur.

A prospective study of 100 consecutive unilateral fractures of the shaft of the femur was performed to delineate the incidence of, and the factors predisposing to, heterotopic ossification about the hip after intramedullary nailing. Bone debris from reaming of the endosteal canal is deposited in the soft tissues surrounding the site of insertion of the nail, and we postulated that this debris may stimulate the formation of heterotopic bone and that decreasing the amount of debris left in the tissues after nailing may decrease the amount of heterotopic ossification. To test this theory, the patients were treated with routine intramedullary nailing and were randomly divided into two groups. In Group I, the operative incision was irrigated with 250 milliliters of normal saline solution with use of a bulb syringe before the wound was closed, and in Group II, the incision was irrigated with 3000 milliliters of normal saline solution with use of pulsatile lavage. The two groups were similar in all other respects. Eighty patients (eighty fractures; forty in Group I and forty in Group II) were available for follow-up and were evaluated in a blind fashion after the fracture had united. A grading system that was based on the length of the heterotopic ossification, as measured on antero-posterior radiographs of the hip, was used. In thirty-two of the patients (40 per cent), no heterotopic ossification developed, whereas minimum or mild ossification developed in twenty-seven patients (34 per cent). Moderate ossification developed in twelve patients (15 per cent) and severe ossification, in nine patients (11 per cent).(ABSTRACT TRUNCATED AT 250 WORDS)

Pelvic ring disruptions: effective classification system and treatment protocols.

From January 1, 1985, to September 10, 1988, 210 consecutive patients with high-energy pelvic ring disruptions (exclusive of acetabular fractures) were admitted to a statewide referral center for adult multiple trauma. They were treated by one of four attending orthopaedic traumatologists per protocol as determined by their injury classification and hemodynamic status; the injury classification system was based on the vector of force involved and the quantification of disruption from that force, i.e., lateral compression, anteroposterior compression, vertical shear, and combined mechanical injury. Of the 210 patients, 162 had complete charts: 126 (78.0%) were admitted directly from the scene, 110 (67.9%) were injured in motor vehicle or motorcycle accidents, 25 (15.0%) were admitted in shock (blood pressure less than 90 mm Hg), the average Glasgow Coma Score was 13.2, and the average Injury Severity Score was 25.8. Treatment of the pelvic fracture included the following methods (alone or in combination): acute external fixation (45.0; 28.0%), open reduction/internal fixation (22; 13.5%), acute arterial embolization (11; 7.0%), and bedrest (68; 42.0%). Overall blood replacement averaged 5.9 units (lateral compression, 3.6 units; anteroposterior compression, 14.8 units; vertical shear, 9.2 units; combined mechanical, 8.5 units). Overall mortality was 8.6% (lateral compression, 7.0%; anteroposterior, 20.0%, vertical shear, 0%; combined mechanical, 18.0%). The cause of death was associated with the pelvic fracture in less than 50%; no patient with an isolated or vertical shear pelvic injury died. We conclude that the predictive value of our classification system (incorporating appreciation of the causative forces and resulting injury patterns) and our classification-based treatment protocols reduce the morbidity and mortality related to pelvic ring disruption.

Acetabular depression fracture accompanying posterior fracture dislocation of the hip.

The acetabular depression fracture is defined as a rotated, impacted, osteocartilaginous fragment of the posteromedial acetabulum that occurs in conjunction with a posterior fracture dislocation of the hip. Displacement of this fracture fragment creates incongruity of the posterior acetabular articular surface and the potential for hip joint instability. A retrospective review of hip dislocations over a 3-year period disclosed 75 posterior fracture dislocations of the hip. A total of 71 hips had computerized tomography (CT) scanning after successful closed reduction of the dislocation. Of the 75 dislocations, 58 were treated with open reduction and internal fixation for reproducible posterior subluxation or redislocation upon clinical examination, non-concentric closed reduction, and/or unacceptable articular fracture displacement. The acetabular depression fracture was identified in 17 cases (23%). A total of 16 were found on preoperative CT scans, and one was discovered at the time of open reduction. Preoperatively, each of these injuries demonstrated posterior instability with hip flexion less than 90 degrees. Treatment consisted of disimpaction of the fragment with elevation to the level of the concentrically reduced femoral head. The fragment was stabilized with packed cancellous bone graft obtained from the greater trochanter. The separate posterior lip fragment was then reduced and internally stabilized to ensure reduction of the acetabular depression fragment. We conclude that this variant of the posterior fracture dislocation of the hip occurs in a significant percentage of these injuries. Preoperative recognition of this fracture may correlate with posterior hip instability, and its presence may be an indication for open reduction and internal fixation of the fracture. Long-term studies of this lesion are still needed.

Intramedullary nailing of open fractures of the femoral shaft.

The cases of eighty-six patients in whom eighty-nine open fractures of the femoral shaft had been treated by intramedullary nailing with reaming were retrospectively reviewed. Twenty-seven fractures were classified as grade-I open fractures; sixteen, as grade-II open fractures; and forty-six, as grade-III open fractures. Immediate intramedullary nailing was done for fifty-six fractures, and delayed stabilization (five to seven days after delayed closure of the wound) was done for thirty-three fractures. A prerequisite for immediate intramedullary nailing was that irrigation and debridement of the open wound be done within eight hours after injury. All fractures healed in an average of 5.2 months. No infections occurred in the sixty-two grade-I, grade-II, or grade-IIIA open fractures, regardless of whether immediate or delayed intramedullary nailing was performed. Of the twenty-seven grade-IIIB fractures, infection developed in three: in one after immediate intramedullary nailing and in two after delayed intramedullary nailing. We concluded that, if a thorough and timely debridement can be accomplished, immediate intramedullary nailing of grade-I and grade-II open fractures of the femoral shaft does not increase the risk of postoperative infection. Selected patients who have a grade-III open fracture may be candidates for immediate intramedullary stabilization, depending on the degree of the patient's associated injuries and the extent of disruption and contamination of the soft tissues of the thigh.

The role of post-operative radiation in the prevention of heterotopic ossification in patients with post-traumatic acetabular fracture.

Heterotopic ossification (HO) with subsequent pain and limitation of motion of the lower extremity is a common and significant problem for patients who suffer traumatic acetabular fracture (TAF). The incidence of heterotopic ossification is markedly increased for patients requiring surgical repair depending on the degree of trauma and the type of surgical repair necessary. Radiation therapy (RT) has proven to be the most effective surgical adjunct for the prevention of heterotopic ossification in patients undergoing total hip replacement (THR), but has not been reported in patients with traumatic fracture and repair. This report details an experience with patients treated at a Shock Trauma Center with extensile repair and immediate (within 48 hr) post-operative radiation therapy given as 5 daily fractions of 2 Gy in 5 to 7 days to a total dose of 10 Gy using megavoltage radiation therapy. A total of 30 consecutive patients (RT group) have been treated at our institution since June 1985. The last 20 patients treated with surgery only (non-RT group) prior to initiation of this study were used as a control group. Heterotopic ossification was seen to some degree in 50% of all radiation therapy patients, but was severe in only three of 30 (10%) of cases [three (10%) had Brooker III HO and no patients had ankylosis (Brooker IV HO)]. In contrast, some degree of heterotopic ossification was seen in 90% of the non-radiation therapy patients, and was severe in 10 of 20 (50%) of patients [seven (35%) had Brooker III HO whereas three (15%) had ankylosis (Brooker IV)]. This difference is significant for both total incidence and incidence of severe cases (p less than 0.01). This reduction in heterotopic ossification incidence approaches the magnitude reported for high-risk patients with total hip replacement. Even though the incidence of severe heterotopic ossification after radiation therapy for total hip replacement is approximately 5% and for traumatic acetabular fracture patients it is double (10%), the actual incidence of heterotopic ossification without radiation therapy is different in the two conditions. For total hip replacement, the incidence is about 30% and for traumatic acetabular fracture it is 50%. Radiation therapy has again proven itself to be an excellent surgical adjunct to prevent heterotopic ossification, this time in traumatic acetabular fracture patients.

Pelvic fracture in multiple trauma: classification by mechanism is key to pattern of organ injury, resuscitative requirements, and outcome.

Three hundred forty-three multiple trauma patients with major pelvic ring disruption were studied and subdivided into four major groups by mechanism of injury: antero-posterior compression (APC), lateral compression (LC), vertical shear (VS), and combined mechanical injury (CMI). Acetabular fractures which did not disrupt the pelvic ring were excluded. The mode of injury was: MVA, 57.4%; motorcycle, 9.3%; fall, 9.3%; pedestrian, 17.8%; crush, 3.8%. The LC and APC groups were divided into Grades 1-3 of increasing severity. The pattern of organ injury: including brain, lung, liver, spleen, bowel, bladder, pelvic vascular injury (PVASI), retroperitoneal hematoma (RPH) and complications: circulatory shock, sepsis, ARDS, abnormal physiology, and 24-hr total fluid volume administration were all evaluated as a function of mortality (M). As LC grade increased from 1 to 3 there was increased % incidence of PVASI, RPH, shock, and 24-hr volume needs. However, the large incidence of brain, lung, and upper abdominal visceral injuries as causes of death in Grade 1 and 2 fell in LC3, with limitation of the LC3 injury pattern to the pelvis. As APC grade increased from 1 to 3 there was increased % injury to spleen, liver, bowel, PVASI with RPH, shock, sepsis, and ARDS, and large increases in volume needs, with important incidence of brain and lung injuries in all grades. Organ injury patterns and % M associated with vertical shear were similar to those with severe grades of APC, but CMI had an associated organ injury pattern similar to lower grades of APC and LC fractures. The pattern of injury in APC3 was correlated with the greatest 24-hour fluid requirements and with a rise in mortality as the APC grade rose. However, there were major differences in the causes of death in LC vs. APC injuries, with brain injury compounded by shock being significant contributors in LC. In contrast, in APC there were significant influences of shock, sepsis, and ARDS related to the massive torso forces delivered in APC, with large volume losses from visceral organs and pelvis of greater influence in APC, but brain injury was not a significant cause of death. These data indicate that the mechanical force type and severity of the pelvic fracture are the keys to the expected organ injury pattern, resuscitation needs, and mortality.

Anterior screw fixation of posteriorly displaced type II odontoid fractures.

Posteriorly displaced Type II odontoid fractures (Type II-P) are difficult to stabilize in an anatomic position with accepted methods of posterior atlantoaxial arthrodesis. Nine patients with Type II-P odontoid fractures with 4 to 15 mm displacement were treated with anterior odontoid screw stabilization. Seven of these patients had associated fractures or defects of the posterior arch of the first cervical vertebra (C1). Atlantoaxial posterior arthrodesis in these patients would not have been possible initially because of the lack of structural integrity of the posterior arch of C1. Two patients, later in the study, had no injury to the ring of C1. The odontoid fractures were stabilized with two 4.0-mm cancellous screws inserted through an anterior approach to the neck under fluoroscopic control with the skin incision at the C5 level. Preoperative reduction of the displaced odontoid process and immediate operative stability of the atlantoaxial complex were obtained in each case. No neurological complications related to the procedure occurred. Two patients died of causes unrelated to their cervical fracture surgery. The 7 patients who survived were followed for a minimum of 6 months. Fracture union and cervical stability were demonstrated in each of the surviving patients, without evidence of screw loosening or loss of fixation. Normal range of motion of the neck was documented at follow-up in all surviving patients. Although this series represents a limited experience with this treatment technique, anterior odontoid screw fixation has significant advantages over accepted methods of cervical stabilization for Type II-P odontoid fractures.(ABSTRACT TRUNCATED AT 250 WORDS)

Early prophylactic bone grafting of high-energy tibial fractures.

Fifty-three high-energy tibial fractures treated with early prophylactic posterolateral bone grafting were retrospectively reviewed. The bone-grafting procedures were performed at a mean of ten weeks following injury and at a mean of eight weeks following soft-tissue coverage. Ninety-six percent of the fractures had associated injuries with a mean injury severity score of 20.9. Seventy-nine percent of the fractures were classified as Grade III open fractures, and 40% had bone loss greater than 50% of the cortical circumference. Ninety-six percent of the fractures healed at a mean time of 43 weeks after injury. Segmental bone loss and soft-tissue injury requiring flap coverage were the best predictors of prolonged time to union. Comparison with a matched historical control group of tibial fractures not receiving early bone grafts revealed a mean reduction in time to union of 11.7 weeks (p = 0.03). The incidence of chronic osteomyelitis was 1.9%. These results are attributed to early and repeated aggressive debridement, immediate rigid external fixation, early soft-tissue coverage, and early posterolateral bone grafting. Recommendations include posterolateral cancellous bone grafting two weeks following wound closure by delayed primary closure, split-thickness skin graft, or local rotational myoplasty. A six-week delay following freely vascularized soft-tissue coverage prior to bone grafting is suggested.

Acute compartment syndrome of the thigh. A spectrum of injury.

Twenty-one compartment syndromes of the thigh in seventeen patients were identified for retrospective review. Ten of the compartment syndromes were associated with an ipsilateral femoral fracture; five of these femoral fractures were open. In five patients, the syndrome followed femoral intramedullary stabilization. The remaining eleven syndromes followed blunt trauma to the thigh, prolonged compression by body weight, or vascular injury. The patients who were awake and alert at the time of the examination complained of intense pain in the thigh, and they had neuromuscular deficits. For the patients who could not cooperate with a subjective physical examination because they were under general anesthesia or because of associated injuries, the measurement of compartment pressure assumed a more important diagnostic role. All of the patients had tense swelling of the involved thigh. The predisposing risk factors for the development of compartment syndromes of the thigh, which are common in the multiply injured population, include: systemic hypotension, a history of external compression of the thigh, the use of military antishock trousers, coagulopathy, vascular injury, and trauma to the thigh, with or without a fracture of the femur. In approximately one-half of these patients, a crush syndrome developed, with myoglobinuria, renal failure, and collapse of multiple organ systems. Eight patients (47 per cent) died as a result of multiple injuries. Of the nine patients (ten compartment syndromes) who survived, infection developed at the site of the fasciotomy in six. Follow-up examination revealed marked morbidity, including sensory deficit and motor weakness of the lower extremity.(ABSTRACT TRUNCATED AT 250 WORDS)

The value of internal oblique radiographs for posterolateral bone grafting of the tibia.

A 35 degrees internal oblique radiographic view of the tibia was used for the purpose of demonstrating posterolateral tibial bone grafts. This radiograph of the supine patient is made by internally rotating the affected leg 35 degrees obliquely toward the midline. This view eliminates superimposition of both the tibia and fibula on the graft. This method of radiographic evaluation has been found useful in visualization of graft margins intraoperatively and assessing bone graft incorporations in clinical follow-up evaluations. The authors recommend 35 degrees oblique views in preference to anteroposterior and lateral views for patients who have had posterolateral bone grafts of the tibia performed.

Structural stiffness of the Hoffmann simple anterior tibial external fixation frame.

Tibial external fixation frames were constructed on aluminum tube simulating tibia bone. A 20-mm gap was left at the fracture site in order to measure the structural stiffness of the frame rather than the aluminum tube. The performance of the frames were experimentally evaluated and quantified using tests which simulated the loading conditions encountered in normal walking. These included axial compression, anteroposterior (AP) bending, lateral bending and torsional loading of the frame. The parameters studied were (a) number of fixation pins, (b) number of connecting rods and (c) location of clamps on the pins. Four constants were evaluated from these tests using various structural configurations of the frames; these resulted in four stiffness coefficients in compression, AP bending, lateral bending and torsion. Stiffnesses of various frames with different geometric configurations were compared by comparing their appropriate stiffness coefficients. Such comparison can set forth a quantitative guideline in selecting a suitable frame configuration for the type of injury and condition of fracture pattern. This type of quantitative analysis can also be useful in modifying the frame during the postoperative bone healing process.