The effect of fibular malreduction on contact pressures in an ankle fracture malunion model

Radiographic healing of conservative versus operative management of supination-external rotation II fractures in a smoking and premature weight-bearing population

The treatment of supination-external rotation II fibular fractures continues to be an area of debate. In the event of minimal displacement at the fracture, both surgical management and casting have been supported. This study aims to compare the time interval of radiographic healing in both the surgically and conservatively managed patient. Additional factors such as premature weight bearing and smoking were also examined. Fifty-two charts were examined retrospectively. This included 26 patients in both the surgical and conservative populations. Radiographs were examined for the presence of healing. Anterior-posterior, mortise, and lateral-view x-rays were examined. The presence of cortical bridging and a resolution of fracture line primarily on lateral view at the posterior spike were used to evaluate healing. The mean time for cortical bridging to occur was 89.38 days in the conservative group and 48.69 days in the surgical group. Mean times for healing were significantly longer in both smokers and patients who prematurely bore weight when treated in both the surgical and conservative populations. In the treatment of isolated fibular fractures, surgical intervention appears to offer a faster time to radiographic healing. Smoking and premature weight bearing are shown to prolong the time to radiographic healing in both the surgically and conservatively treated patient populations.

Delayed open reduction and internal fixation of a neglected fracture dislocation of the ankle

Neglected fracture dislocations of ankle are rare in western countries. Failure to achieve anatomic reduction is associated with a poor prognosis. We present a case of a patient with a neglected Weber B fracture of the fibula with postero-lateral subluxation of the ankle. In theatre, the subluxation could not be reduced, and a posterior and lateral soft tissue release was performed. Granulation tissue was removed from the medial gutter. The fibular fracture was reduced and fixed with a six-hole dynamic compression plate. Post-operative radiographs was satisfactory and the patient was followed up for 12 months with full range of movement and function of the joint. In our case, correction was not obtained by osteotomy of the lateral malleolus alone, and medial and posterior soft tissue release was required. This was due to disruption of the deltoid ligament and posterior tibiofibular ligament and the associated scar tissue. Previous studies have shown that, if anatomic reduction is achieved, results with delayed surgery can be as good as those obtained with immediate surgery. Surgically correcting an old fracture dislocation is a difficult undertaking due to soft-tissue contractures and malunited fractures. It is important to preserve as much soft tissue attachments and periosteum to prevent avascular necrosis.

Distal tibial metaphyseal fractures: the role of fibular fixation

Distal tibial extra-articular fractures are often a result of complex high-energy trauma, which commonly involves associated fibular fractures and soft tissue injury. The goal of tibial fixation is to maximise fracture stability without increasing soft tissue morbidity from surgical intervention. The role of adjunctive fibular fixation in distal tibial metaphyseal fractures has been controversial; although fibular fixation has been shown to improve stability of distal tibial fractures, there has been increased potential for soft tissue-related complications and a delay to tibial fracture healing. Adjunctive fixation of concomitant fibular fractures without associated syndesmotic or ankle pathology is not necessary in surgically stabilised extra-articular metaphyseal fractures of the distal tibia.

Contribution of articular surface geometry to ankle stabilization

BACKGROUND

Passive ankle stability under weight-bearing conditions has been found to depend substantially on the role of the articular surface geometry. In the present study, it was hypothesized that, in the ankle under axial loading, contact-stress changes in response to alterations of external load involve reproducible and specific patterns to maintain ankle stability.

METHODS

Six cadaver ankles with the peri-ankle ligaments intact were tested. Each specimen, held at several predetermined ankle positions under a primary one-body-weight axial force, was subjected to an additional secondary load. The secondary load-specifically, anterior/posterior shear force, inversion/eversion torque, or internal/external rotation torque-was applied independently, while motion associated with the two other secondary loading directions was unconstrained. Contact stress in the tibiotalar articulation was monitored by a real-time contact-stress sensor. Site-specific stress changes solely due to secondary loading at each load/position were identified by subtraction of the corresponding axial-force-only baseline distribution. The role of these stress changes in ankle stabilization was studied for each specimen by analyzing the data with a computer model of ankle geometry.

RESULTS

In the cadaver experiment, anterior and posterior shear forces caused reproducible positive changes in articular contact stresses on the anterior and posterior regions, respectively. Similar changes with version torques occurred on the medial and lateral regions. Positive changes with internal/external rotation torques occurred at two diagonal locations: anterolateral and posteromedial, or anteromedial and posterolateral. In the model analysis, these stress-change patterns were found to be effective in ankle stabilization, and the levels of contribution by the articular surface were calculated as accounting for approximately 70% of anterior/posterior stability, 50% of version stability, and 30% of internal/external rotation stability.

CONCLUSIONS

The documented changes in contact stress illustrate the major role of articular geometry in passive ankle stabilization. The levels of contribution by the articular surface that we calculated are consistent with those reported in the literature. These findings support the conceptual mechanism of ankle stabilization by redistribution of articular contact stress.

Detection of fibular torsional deformities after surgery for ankle fractures with a novel CT method

BACKGROUND

Substantial fibular torsional deformities were detected after surgery for ankle fractures combined with a lesion of the syndesmotic complex using a novel CT analyzing method.

METHODS

In a prospective study, 61 patients with ankle fracture dislocations were treated with trans-syndesmotic screw fixation of the distal tibiofibular joint. Postoperative axial CT scans of both lower legs under standardized leg positioning conditions were made and analyzed with three different methods. Method 1 (M1) used proximal and distal CT planes of the lower leg for detection of the fibular torsional angle, method 2 (M2) considered only the angle at the distal tibiofibular joint, and method 3 (M3) measured the angles between the fibular and tibial tangents at the distal tibiofibular joint. Twenty patients with fibular torsional asymmetries of more than 10 degrees were evaluated clinically 6 to 34 months postoperatively with the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Score.

RESULTS

Thirty-five of the 61 patients had torsional side-to-side differences of more than 10 degrees. M1 and M2 showed statistically significant differences compared to M3 (p = 0.001). Validity was controlled by interobserver data, variation coefficients were low for M1 and M2. Clinically, six of 20 patients with torsional differences of more than 10 degrees had excellent results, while seven had good results and seven had moderately functional results. Six of the seven with moderate results had fibular torsional differences of more than 15 degrees, two of the seven patients with good outcomes. Torsional results of M1 and M2 correlated with the AOFAS score (r = -0.506).

CONCLUSIONS

Of the 61 ankle fractures with ruptures of the syndesmotic complex, 25% showed torsional side-to-side differences of more than 10 degrees on proximal and distal CT planes. This CT technique correlated with the AOFAS score and could help determine when early operative revision is indicated.

Revisiting the concept of talar shift in ankle fractures

BACKGROUND

In 1976, Ramsey and Hamilton published a classic experiment investigating the biomechanical effects of talar shift in a simple ankle fracture model. Their finding was that 1 mm of talar shift resulted in a 42% decrease in tibiotalar contact surface area. Based on this conclusion, 1 mm of talar shift became the recognized indication for operative fixation.

METHODS

Twelve cadaver ankles were dissected and the distal tibia coated with carbon powder. A 70-kg load was applied to the distal tibia that resulted in transference of the carbon onto the talus. The contact surface area was determined at 0, 1, 2, 4 and 6 mm of talar shift using spacers fixed in the medial gutter. Tracing paper was used to mark the outline of the contact area and measured using graph paper.

RESULTS

Our results were similar to Ramsey and Hamilton's original experiment. One millimeter of lateral talar shift resulted in 40% loss of contact surface area compared with 42% in the original experiment. A large variance was seen in talar contact surface area depending on the morphology of the ankle joint.

CONCLUSION

Ramsey and Hamilton's original experiment was valid.

Less is more: lag screw only fixation of lateral malleolar fractures

Displaced fractures of the lateral malleolus are typically treated with plate osteosynthesis with or without the use of lag screws, and immobilisation in a plaster cast for up to 6 weeks. Fixation through a smaller incision with less metal, such as lag screw only fixation, would theoretically lead to decreased infection rates and less irritation caused by hardware. The purpose of this study was to evaluate the benefits and success of lag screw only fixation of the lateral malleolus in non-comminuted oblique fractures of the lateral malleolus. A total of 25 patients who had non-comminuted unstable oblique fractures of their lateral malleolus that had been surgically fixed with lag screws only were retrospectively evaluated. All patients were younger than 60 years of age. Evaluation of the success of fixation, complications, resultant mobility and patient satisfaction was based on information gathered from chart reviews, X-ray findings and a standardised questionnaire based on the AOFAS Foot and Ankle Outcomes Questionnaire. These results were compared to an age-matched group of 25 consecutive patients treated with plate osteosynthesis. Of the 25 patients fixed with lag screws, nine had an unstable fracture of the lateral malleolus only, ten were bimalleolar fractures and six were trimalleolar. Eighteen patients were treated with two lag screws, and seven were treated with three lag screws. The bi- and trimalleolar fractures were treated with standard partially threaded cancellous screws. None of the lag screw-only group lost reduction. There were no documented wound infections in the lag screw group as compared to three deep infections in the plate group. Lag screw-only patients reported no palpable hardware as compared to 50% of the plate group. AOFAS scores at a mean of 12 months post-operative were similar in both groups. Lag screw only fixation of the lateral malleolus is a safe and effective method that has a number of advantages over plate osteosynthesis, in particular less soft tissue dissection, less prominent, symptomatic and palpable hardware and a reduced requirement for secondary surgical removal.

Ankle fractures

Although ankle injuries are common, it is imperative for the treating physician to be able to identify the mechanism of injury and accurately restore the normal anatomy of the ankle joint. Attention must be given to restoring the normal alignment and length of the fibula because of its dominant role in controlling talar stability. The medial ankle must not be overlooked, with the role of the deltoid taken into consideration. With a thorough understanding of the anatomy, biomechanics, mechanism of injury, and fixation techniques, repair of the damaged ankle joint can lead to rewarding outcomes for the patient and physician.

Ankle syndesmosis injuries

Physician awareness of ankle syndesmosis injuries is improving. The anatomy involved and the mechanism of injury are extremely relevant for the understanding and treatment of this type of injury. Examination under anesthesia may confirm the syndesmosis instability. Based on those findings, stabilization is the recommended approach.

Dynamic function of the fibula. Gait analysis evaluation of three different parts of the shank after fibulectomy: proximal, middle and distal

The purpose of this case study was to investigate the dynamic features of fibular movement to gait pattern by analyzing the gait of individuals with three different parts of the fibula resected. Gait analyses revealed that proximal fibula resection impaired knee stability, whereas distal fibula resection disturbed ankle kinematics significantly. Except a mild secondary quadriceps weakness, middle fibula resection did not cause a significant biomechanical disturbance on gait.

Ankle joint biomechanics following transepiphyseal screw fixation of the distal tibia

Transepiphyseal screws have traditionally been removed after fixation of pediatric ankle fractures due to concerns about increased forces and contact pressures within the tibiotalar joint secondary to the implant. No study has assessed pressure across the ankle joint after such fixation. Seven adult and two pediatric cadaveric ankles underwent axial loading in a uniaxial material test machine. Each was tested before fixation (control), after fixation (screw in place), and after removal (after screw removal). Three sequential test runs at three loading conditions (approximate body weight, twice body weight, and five times body weight) were performed to simulate forces of standing and ambulation. Total force, peak contact pressure, and contact area were measured with an intra-articular sensor. After screw placement, all loads caused a significant increase in total force versus control. Peak contact pressures after placement also increased significantly. Screw removal subsequently led to a net decrease in force and peak pressure values. Total contact area was unchanged. Concerns regarding subchondral screws in the distal tibia appear warranted. Findings in this study support implant removal following union of such fractures.

The ABJS 2005 Nicolas Andry Award: osteoarthritis and injury at the base of the human thumb: survival of the fittest?

The basal joint complex, consisting of four trapezial articulations providing a foundation for the thumb, defines our anatomic evolution from a Simian ancestry by providing an opposable member. Ironically, the trapeziometacarpal joint also is responsible for the most common malady leading to operative reconstruction in the upper limb for arthritic disease. The paradoxic relationship between these two facts has stimulated investigation that has defined the scientific basis for common surgical procedures and provided a foundation for the development of novel treatments for conditions at the base of the thumb. Patterns of articular surface degeneration are determined by areas of contact loading in the joint. Ligament reconstruction, metacarpophalangeal joint flexion splinting, and extension metacarpal osteotomy for early disease resulting from instability all have biomechanical justification for their clinical application. Likewise, percutaneous pinning of Bennett's fracture dislocation is predicated on reestablishing functional continuity of the beak ligament and unloading the palmar joint surfaces. For advanced disease, ligament reconstruction has become the cornerstone of arthroplasty. Perhaps most importantly, the trapeziometacarpal joint as an instability model can provide insight into the interplay of mechanical and biological factors in producing the primary lesion associated with osteoarthritis.

Articular contact at the tibiotalar joint in passive flexion

The knowledge of the contact areas at the tibiotalar articulating surfaces during passive flexion is fundamental for the understanding of ankle joint mobility. Traditional contact area reports are limited by the invasive measuring techniques used and by the complicated loading conditions applied. In the present study, passive flexion tests were performed on three anatomical preparations from lower leg amputation. Roentgen Stereophotogrammetric Analysis was used to accurately reconstruct the position of the tibia and the talus at a number of unconstrained flexion positions. A large number of points was collected on the surface of the tibial mortise and on the trochlea tali by a 3-D digitiser. Articular surfaces were modelled by thin plate splines approximating these points. Relative positions of these surfaces in all the flexion positions were obtained from corresponding bone position data. A distance threshold was chosen to define contact areas. A consistent pattern of contact was found on the articulating surfaces. The area moved anteriorly on both articular surfaces with dorsiflexion. The average position of the contact area centroid along the tibial mortise at maximum plantarflexion and at maximum dorsiflexion was respectively 58% posterior and 40% anterior of the entire antero-posterior length. For increasing dorsiflexion, the contact area moved from medial to lateral in all the specimens.

Trimalleolar fractures with impaction of the posteromedial tibial plafond: implications for talar stability

BACKGROUND

Trimalleolar fractures usually include a lateral malleolar fracture, a triangular fracture of the posterolateral corner of the tibial plafond, and a horizontal or oblique fracture of the medial malleolus. A subtype of a trimalleolar fracture is reported, differing in the shape and extent of the medial malleolar fracture and the posterior lip fracture, with implications for treatment.

METHODS

In a 3-year period, 10 patients were treated for a trimalleolar fracture with a multifragmentary transverse fracture of the entire posterior tibial lip, including the posterior colliculus of the medial malleolus. The radiographs of all patients showed a pathognomonic double-contour or flake-fragment sign above the medial malleolus. One patient's posteromedial fracture was not initially recognized and he had a standard lateral fracture repair. A double posterior approach was used in nine patients, with fracture repair proceeding from medial to lateral. Intraoperatively, eight of nine patients had impacted osteochondral fragments at the posteromedial corner of the tibial plafond that blocked anatomic reduction and allowed posteromedial subluxation of the talus.

RESULTS

Nine patients had anatomic reconstruction of the posteromedial corner. All fractures healed, and function was normal at one year. One patient had moderate loss of joint space. The patient with the malunited fracture developed symptomatic posteromedial instability of the talus and required an osteotomy of the malunited fragment. He had a good result at 18 months.

CONCLUSIONS

This unique subtype of trimalleolar fracture has distinct radiological features and implications for the strategy of the operative treatment. If recognized immediately and treated appropriately, the results were excellent. If missed initially, reconstructive osteotomy was possible and led to a good result.

Revision of malunited ankle fractures

Malunion of an ankle fracture can lead to considerable pain and loss of function. Restoration of the normal anatomical alignments can restore function and minimize the onset of degeneration that will lead to severe arthrosis requiring an arthrodesis. This article outlines common causes of ankle malunion and treatment options.

Corrective ankle osteotomies

Corrective ankle osteotomies are periarticular osteotomies of the fibula, distal tibial metaphysis, or distal tibial metaphyseal diaphyseal junction. These osteotomies are indicated when angular, rotational, or translational malalignment is present. The author presents a review of the literature and in-depth surgical technique for each procedure, as well as a review of how to prevent and address the most common complications encountered.

Corrective-elongation osteotomy without bone graft for old ankle fracture with residual diastasis

The main principle for treatment of ankle fractures is anatomic reduction until bony union is achieved. Old fractures of the ankle with residual diastasis, however, may cause persistent pain, joint effusion, and range-of-motion limitation, and make eventual ankle arthrodesis inevitable. Restoration of the integrity of the ankle mortise is the determining factor for successful repair of this type of ankle fracture. Old ankle fracture, where malunion has already occurred, is a great challenge for the orthopedic surgeon. Twelve such patients were treated by means of reconstructive corrective-elongation osteotomy without bone graft at the authors' institution from 1997 to 1999. These patients had persistent symptoms and radiographic evidence of a fibula that had healed in a shortened, rotated position, resulting in widening of the ankle mortise. The average time interval between injury and reconstructive operation was 18 months. At follow-up, which averaged 34 months, greatly improved ambulation and level of joint function was noted for all patients, and follow-up x-ray confirmed good ankle mortise geometry. The short-term results for these patients were good, with further follow-up planned to determine efficacy long term. In conclusion, reconstructive corrective-elongation osteotomy is a worthwhile procedure for old ankle fracture with malunion, and it can also postpone degenerative change in the ankle joint.

Effects of isolated Weber B fibular fractures on the tibiotalar contact area

Fractures of the lateral malleolus can occur without rupture of the deltoid ligament or fracture of the medial malleolus. Controversy exists regarding the necessity of surgery on supination-external rotation stage II ankle fractures. Theoretically, as long as the medial structures are intact, the talus cannot displace enough to cause degenerative arthritis of the ankle joint. The purpose of this study was to measure changes in contact area between the tibial plafond and the talar dome with serial displacement of the distal fibula in both a lateral and a superolateral direction. Twelve cadaver lower extremities were used. Distal fibular fractures were replicated by creating an osteotomy. Displacement was accomplished with a customized apparatus that displaced and held the distal fibula in a malaligned position. Tibiotalar contact area was measured with pressure sensitive film at the following intervals of fibular displacement: 0 mm, laterally 2 mm and 4 mm, and then posteriorly and superiorly 2 mm and 4 mm. A servohydraulic testing apparatus was used to apply the same physiologic load to all limbs while measuring contact area. Key independent variables included the direction and amount of displacement of the distal fibula. Mean tibiotalar contact area decreased from baseline (no displacement) 361.1 mm2 (SD +/- 49.0) to 162.2 mm2 (SD +/- 81.3) and 82.6 mm2 (SD +/- 30.6) for 2 mm and 4 mm lateral displacement of the distal fibula respectively. With posterior/superior displacement of 2 mm and 4 mm mean tibiotalar contact decreased to 219.3 mm2 (SD +/- 56.7) and 109.2 mm2 (SD +/- 39.0), respectively. Statistical significance was found (P <.001) when comparing normal ankle alignment with displaced fractures at all levels of displacement.

Position of the distal fibular fragment in pronation and supination ankle fractures: a CT evaluation

BACKGROUND

Although classically the fibula has been reported to be in external rotation after supination-external rotation (SER) or pronation-external rotation (PER) ankle fractures, a previous CT study demonstrated that what had traditionally been interpreted as external rotation of the distal fibular fracture fragment is actually internal rotation of the proximal fibular fragment. The purpose of this study was to evaluate a series of CT scans in patients who have suffered type IV SER or PER ankle fractures to assess the rotational deformity of the fibular fragment.

MATERIALS AND METHODS

CT scans of the injured and uninjured extremities were performed on 30 extremities which had sustained either SER (21) or PER (9) injuries. The rotational relationship between the tibia and fibula was determined by a measured rotational ratio. A qualitative assessment of the rotational relationship between the tibia and fibula above, at, and below the fracture site at the level of the mortise was also performed. The difference in the ratio (calculated by subtracting the rotation ratio of the normal side from the fracture side) demonstrated whether the fractured fibula is externally or internally rotated compared to the uninjured side.

RESULTS

The average rotational ratio difference above the fracture compared to below the fracture for the SER group demonstrated significant external rotation (p < .001). The PER fracture also demonstrated external rotation of the distal fragment compared to the proximal fragment (p = .002). Additionally, qualitative assessment of the relationship demonstrated no obvious change in the rotational relationship in any patient above the fracture site except one where mild internal rotation of the proximal fragment was noted. However, at the level of the mortise, all had a normal talofibular rotational relationship while 24 of 30 had widening of the medial clear space with external rotation clearly evident on 15 of these 24 scans.

CONCLUSION

Our study demonstrated that the distal fibular fragment in both SER and PER fractures is externally rotated relative to both the contralateral normal side and compared to the proximal fibular fragment.

Peroneus longus ligamentoplasty for chronic instability of the distal tibiofibular syndesmosis

The distal tibiofibular syndesmosmotic ligament complex is important for dynamic stability and congruency of the ankle joint. Syndesmotic lesions in the ankle fracture-dislocations are well recognized and classified systematically. Chronic insufficiency of the syndesmosis leads to a lateral shift of the talus and under eversion stress permits a pathological rotation of the talus. There is also retroversion of the distal fibula representing a painful deformity. Little experience exists with surgical reconstruction of the syndesmosis. This article describes a new ligamentoplasty with a split peroneus longus tendon graft that mimics the normal anatomic conditions of the syndesmotic complex in 16 patients with symptomatic chronic syndesmotic insufficiency after pronation-external rotation and pronation abduction injuries to the ankle joint. Postoperatively, no infections or hematomas were seen. One patient had asymptomatic breakage of the syndesmosis screw; one patient had a 10 degree decrease of dorsiflexion at the ankle because of a partial anterior tibiofibular synostosis. Fifteen of 16 patients had pain relief at a mean follow-up period of 16.4 months (range, 13-29 months); all patients had relief of the chronic swelling of the ankle and the giving way. The mean Karlsson score at follow-up was 88 (range, 70-100) points. It may be concluded that peroneus longus ligamentoplasty in a preliminary series resulted in reliable ankle stability and considerable pain relief in patients with chronic syndesmotic instability.

Malunion following trimalleolar fracture with posterolateral subluxation of the talus--reconstruction including the posterior malleolus

Malunion after a malleolar fracture can include a displaced posterior malleolus with associated posterolateral subluxation of the talus. Corrective osteotomy including the posterior malleolus was performed in four patients. Joint congruity was obtained in every case. The patients were followed for 46 to 80 months postoperatively. They all experienced an improvement in pain and three of four patients were unlimited in their walking capacity. Mild to moderate residual symptoms were frequent. The symptoms were attributed to the damage of the cartilage and soft-tissues both from the initial injury and from weightbearing on the incongruous joint. Discrete, non-progressive osteophytes were seen in all patients. Delay in reconstruction did not preclude a good result, although early reoperation is felt to be preferable.

Surgical treatment of a displaced lateral malleolus fracture: the antiglide technique versus lateral plate fixation

OBJECTIVES

To assess the outcomes of the surgical management of "isolated" displaced lateral malleolar fractures, comparing the techniques of lateral plating and antiglide plating as described previously.

DESIGN

This is a retrospective review, being largely a surgeon-randomized comparative study.

SETTING

The study was carried out at a university teaching hospital that serves as a provincial trauma referral service and provides local community care. The senior surgeons are all orthopaedic trauma subspecialists.

PATIENTS

A total of 193 patients meeting our inclusion criteria, with isolated lateral malleolus fractures surgically treated at the Vancouver General Hospital between 1987 and 1998, were studied.

INTERVENTION

Eighty-five were treated with antiglide plating, whereas the remaining 108 patients underwent traditional lateral plating.

MAIN OUTCOME MEASURES

The functional results were evaluated with the ankle scoring system described previously. We also compared the complication rates, including failure of fixation, infection, wound dehiscence, and need for hardware removal.

RESULTS

Both groups were comparable for age, sex distribution, mechanism of injury, and occupation. There was no difference in ankle score, function, and infection rate. The incidence of wound dehiscence and reoperation for hardware removal was slightly higher in the lateral plate group, but the difference was not statistically significant.

CONCLUSIONS

The outcome of the surgical management of a displaced lateral malleolus fracture is comparable with both techniques. Although few studies have reported some advantages using the antiglide technique, our data do not support one technique over the other.

Intra-articular load distribution in the human ankle joint during motion

The rational treatment of injuries to the ankle is predicated on an understanding of biomechanics of the ankle. While several investigators have reported on three-dimensional dynamic kinematics of the ankle and on the static distribution of pressure within the ankle, it has not been possible to measure intra-articular forces reliably under dynamic conditions. The assumption that the distribution of forces under dynamic conditions is well represented by statically determined forces has not been validated, leaving in question the applicability to dynamic conditions of data obtained under static conditions. This study characterizes an electro-mechanical thin-membrane force transducer with potential for intra-articular use. The sensor was found to yield a reproducible linear response to loads experienced in the ankle, and was insensitive to both a moist environment and shearing forces. On the basis of these results, these force-transducers were placed in axially loaded cadaveric ankles that were either statically or dynamically cycled through a physiologic range of motion. In each of six specimens, sensors were secured to the medial and lateral malleolar articular surfaces, and to articular surfaces of the medial and lateral tibial plafond. Both medial and lateral malleolar-talar forces increased with dorsiflexion. Moving from plantarflexion to dorsiflexion caused an increase in lateral tibio-talar load accompanied by a decrease in the medial tibio-talar loading. There was no significant hysteresis in force-distribution with respect to the direction of sagittal motion. There was no difference between the forces measured under static or dynamic conditions. This study validates the use of static loading methodologies in future studies of force-distribution. Our data in intact ankles closely corresponded to data on forces under dynamic conditions. Dorsiflexion caused an increase in both medially and laterally directed forces towards the malleoli. This is the first demonstration of such forces, which are responsible for the external rotation and lateral translation of the distal fibula that occurs in dorsiflexion of the ankle.

Ankle fractures and syndesmosis injuries

Ankle fractures are one of the most frequently treated injuries in orthopedic traumatology. The simple injuries often are forgiving and are managed easily and appropriately by closed treatment, but more complex injuries require recognition of possible associated injuries and anatomic internal fixation. Although adherence to general guidelines of fracture management usually suffices, some cases do not fall into a well-defined category, and clinicians are called on to use their experience and clinical knowledge to make treatment decisions that best ensure good clinical outcomes.

A different approach to the treatment of the lateral malleolar fractures with syndesmosis injury: the ANK nail

This retrospective study was conducted on a total of 139 cases of fractured ankles involving the fibula above the syndesmosis which were treated with open reduction and internal fixation with the intramedullary ANK nail at the Department of Orthopaedic Surgery at Vakif Gureba Teaching Hospital from 1990 to 1997. We were able to review 128 of these patients after a mean follow-up of 3.1 years (range, 1 - 7 years) including 60 with Weber type B and 68 with Weber type C fractures. The results were evaluated using objective, subjective, and roentgenographic criteria described by Cedell. Ninety-three patients (73%) have obtained good objective results, 28 (22%) fair, and seven (5%) have obtained poor objective results. Subjective rating were 94 patients (74%), good; 26 patients (20%), fair; and eight patients (6%), poor. Good radiological results were found in 99 patients (77%), fair radiological results in 21 patients (17%), and poor radiological results were found in eight patients (6%). It is concluded that the ANK nail could be used for the fixation of the lateral malleolar fracture with tear of the syndesmosis ligament.