Biomechanical evaluation of intra articular calcaneal fracture and clinical radiographic correlation

Abstracts

O presente estudo teve o objetivo de oferecer uma avaliação clínica, radiográfica e biomecânica de pacientes com fratura intraarticular de calcâneo, submetidos à redução aberta e fixação interna. A amostra consistiu em 22 pacientes, 20 do sexo masculino e dois do sexo feminino, com idade média de 40,95 (± 11,63) anos. Os autores realizaram avaliações radiográficas do ângulo de Böhler e Gissane, no pré e no pós-operatório, além de utilizarem a tomografia computadorizada para avaliação da classificação de Sanders. A avaliação da Distribuição da Pressão Plantar foi realizada pelo sistema F-scan. Os resultados clínicos encontrados foram satisfatórios apresentando, pontuação média de 75,5 no critério da AOFAS.. A redução cirúrgica resultou em uma melhora dos ângulos de Böhler e Gissane. O estudo mostrou diferenças estatisticamente significantes entre o antepé o retropé fraturados no que tange sobre a área de contato, pressão e força de reação do solo. Os valores encontrados para estes parâmetros foram maiores no retropé que no antepé fraturados. A trajetória de Pressão (COP) foi menor no pé fraturado que no pé normal. Encontrou-se correlação entre o Ângulo de Gissane após a redução e o Segundo Pico de Força, indicando que quanto melhor a redução deste ângulo , melhor a impulsão. Também encontrou-se a correlação entre a pontuação AOFAS e o Primeiro Pico de Força, mostrando que quanto melhor o resultado clínico melhor o apoio do retropé.

Calcâneo; Biomecânica; Fraturas

ORIGINAL ARTICLE

Biomechanical evaluation of intra articular calcaneal fracture and clinical radiographic correlation

Marcos Emilio Kuschnaroff Contreras^I; Adriane Mara de Souza Muniz^II; Juliana Barcellos de Souza^II; Aluisio Otavio Vargas Avila^III; Noé Gomes Borges Junior^IV; Diogo Rath Fingerl Barbosa^V; Luciano Manoel Martins Kroth^VI; Marcos dos Reis Filho^VII

^IDoctor Head of the Foot and Ankle Group Orthopedics and Traumatology Service of Governador Celso Ramos (HGCR). Mastering of Biomechanical Department of the of the State University of Santa Catarina.

^IIPhysiotherapist. Master of the Biochemical Department of State University of Santa Catarina.

^IIIChairman of the Biomechanical Department of University of Santa Catarina. Phd in Biomechenical at Valderbilt University – Nashiville – Tennesse – USA

^IVProfessor of the Biologics Science of CEFID – Santa Catarina University. PhD in Biophysics at Clermont 1 – Université dá Auvergne-Clermont – France.

^VResident of the Orthopedics and Traumatology Services of HGCR.

^VIDoctor of the Foot and Ankle of Orthopedics and Traumatology Services. HGCR

^VIIHead of the of Orthopedics and Traumatology Service of Celso Ramos Hospital (1990-2001)

^{Correspondence}

SUMMARY

The present study had an objective to perfom a clinical, radiographic and biomechanical evaluation in patients with calcaneal fractures submitted to open reduction with internal fixation. The sample consisted of 22 patients – 20 male and 2 female with an average age of 40,95 (±11,63) years old. The authors have done radiographic evaluation of the pre and post operatory of Böchler and Gissane angles; furthermore, they used a CT scanning for Sander's classification of calcaneal fractures. The plantar pressure distribution was analyzed with F-scanning system. The results of the intra-articular calcaneal fractures were clinically satisfactory, showed average punctuation with 75,5 in AOFAS criterion. The surgical reduction in a better angle of Böchler and Gissane.

The study showed statistical differences between the forefoot and rearfoot concerning the the contact area, average preassure and strength in the injured foot. The figures found to this parameter were bigger in the rearfoot than the forefoot.

The trajectory of pressure (COP) was shorter in the fractured foot than in the normal foot. The correlation between the angle of Gissane after the reduction and the second peak of force was found, showing as better as the reduction of this angle, the better is the impulsion. It was also found the correlation between the punctuation between AOFAS and the first peak of force, showing as better is the clinical result the better is the foot supporter.

Key words: Calcaneal; Biomechanical; Fracture

INTRODUCTION

The calcaneal is more likely bone to be fractured between the tarsus bone; however there is not a common sense yet about the best type of treatment^(11,16,21). Historically, the calcaneals fractures were treated in a conventional way, however with technological advances, nowadays the treatments tend to decrease the quantity of surgeries and internal fixation⁽¹¹⁾.

According to Slatis et al⁽²⁵⁾ the calcaneal fractures is the most common fracture in adults. These fractures consist of work the high disability trauma due to the long time on leave of their jobs; and also the post operatory results.

Furthermore it shows high incidences in adults and young adults, that is, economic active population.

Lowery et al⁽¹⁰⁾ were responsible for a wide bibliography review of the calcaneal fractures. Since the ancient times, the calcanel fracture has been a controversy issue in Medicine. In 1720, Garongeat described the shattered calcaneal fractures as compressing fractures denoting a complete loss of the anatomy after this fracture. In 1843 Malgaine was the first to describes the anatomical calcaneal fracture⁽¹⁰⁾.

Since Hipocrates the treatment of these fractures were with bands. In 1850 Clark released the fixation of pines. In 1882, Charles Bell started the reduction of these severe fractures, and in 1902, Morestein added the internal fixation. In 1908 Cotton and Wilson described the deformities caused by the calcaneal fractures, and also described the not so severe reduction or several limited reduction following by the treatment with plaster⁽¹⁰⁾.

1930, Bohler was the one to purpose an anatomical classification for the calcaneal fractures, suggesting as treatment a reduction technique with the manipulation, compression and traction associated with the immobilization. In 1951, Essex-Lopresti showed a classification based on fracture trauma mechanism, and this classification remains widely used so far in places where there is an easy approach to computerized tomography (CT). In 1989, Sanders purposed a classification with (CT) and emphasized the posterior surface fracture as a post-diagnoses⁽¹⁰⁾.

The purpose of this study consist in assessing the calcaneal fractures with analyses of plantar pression distribution, in a dynamic way during the bait and relate these clinical diagnoses data, radiographic and tomographic.

METHOD

Within January, 1995 to January of 2001, 61 patients were submitted to intra articular calcaneal surgical treatment, in Governador Celso Ramos Hospital – Florianópolis-SC (GCRH). 22 patients made part of the of the bait evaluation test at the Biomechanical Laboratory of Santa Catarina University, where 24 fractured feet, with at least 15 months followed up (Table 1). The average age was of 40,95 years old (±11,63) ranging from 22 to 59 years old. Twenty patients were male and two female, being 11 cases with the right side access and 9 at the left side, and two cases were bilateral. All the patients were submitted to open reduction by lateral approach, using screw and plate, with only screw and thread or only with Kirschner threads. A transplant of bone was used only in one case. About the trauma mechanism of 19 cases were because of falls from high and three cases for car accidents.

The plantar pressure distribution (PPD) investigation was done with the F-Scan system (TEKSCAN, Inc, Boston, MA),which is a matritial sensor system of resistence and strength. Sensore sole are put is the patients'shoes and these are connected to a CPU unity of a computer with an installed data analyzes system. The patients are advised to stroll in their natural cadence. The acquisition frequency of 120 Hz, time of collection of 6 s)

In order to investigate the PPD the plantar diagram which was divided into forefoot and rearfoot, the t -test was given to independent samples (p< 0,05) at the forefoot and rearfoot same side This data were compared to the results obtained in clinical, radiographs and tomography evaluation.

The patients were clinically evaluated by the American organization of foot and ankle society (AOFAS) criterion for the rearfoot, being done by the same instructor. The tomography analyses were made based on Sanders and the radiography by Essex-Lopresti. With the radiography in the profile incidence was measured with theangles of Böhler and Gissane.

RESULTS

The Table 2 shows a radiographic, tomographic and clinical summary of the sample.

With the radiographies the profile incidence were measured using the angles of Böhler and Gissane. The average of the angle of Böhler in the pre-operatory was 6,9º, and the parameters under normality between 25º and 40º ⁽²²⁾. at the post-operation, after surgical reduction, the average angle found was 24º, therefore with an important difference in the pre and post operatory (t=5,70, p<0,001).

The angle of Gissane in the pre-operatory showed an average figure of 109,8º, and 119,3º in the post operatory. It was considered as a normal figure this angle of 140º, with an important difference in the average of the pre and post-operatory angles (t=­2,10,p<0,05). (Table 5)

The clinical discretion with AOFAS for the rearfoot, presented average punctuation of 75.5 points.

The system to make use of the 100 points scale and value pain (40 points), function (50 points) and alinement (10 points).

The Sander's tomographic classification evaluation shows a smooth dominance of type II than the type II and IV, as shown in the Table 3.

About the Essex-Lopresti's radiological classification, 17 fractures were joint depression type and seven of tongue type (Table4).

The results obtained by the F-scan system are shown in the graph 1 to 3, illustrating the results of the contact area, the strength and average pressure in the both sides of the forefoot and rear foot.

When analyzing the plantar pressure distribution of the patients submitted to the unilateralis calcaneal fracturesurgery, we observed the average figures of the contact at the side had important difference between the fractured side of the forefoot and rearfoot (t=-3,95 p<0,001) confirming the larger rearfoot fracture area.(Table 6) (Graph 1).

This fact is due to the deficit in the weight transference to the forefoot during gait with no important difference to the average figures at the non-fracture side.

While analyzing the pressure force on the fractured foot, there were important averages of force of the forefoot and rearfoot fractured side (t=-5,65; p= 0,00004), but no difference of the counter-lateral side. The decrease of the force of the forefoot area (under the peak of force), shows reduction in the strength expulsion during the gait(Table 6) (Graph 2).

The average pressure in the fractured foot showed important difference between the forefoot and rear foot (t=4,93,p=0,0002), with no important difference in the counter lateralis to this variant. There is an important higher pressure under the fractured rearfoot in relation of the one on the forefoot (Table 6) (Graph 3).

Those who had bilateralis fractures, did not show important difference between the average figures of the contact area and between the forefoot and rearfoot.

The Pressure Center Observations (COP), show in the fractured foot, the trajectory was shorter. The COP showed three different behaviors: displacement between the second and first head of the metatarsus (61% of the cases), displacement until the medien foot foot (27%) and COP displacement not coming from the rearfoot (11%).

The different trajectories of the (COP) Pressure Center found are showed in Figure 1, and the sample distribution in Table 7.

The angle of Gissane after the reduction fracture surgery had correlation with the second peak of force (SPF) from the fractured foot (r=0,61; p<0,05), area and pressure of the rearfoot and forefoot fractured.

The angle of Gissane after the reduction fracture surgery Vs SPF in the fractured foot (Graph 4).

The Clinical Criterion AOFAS showed important correlation with the First Peak of Force (FPF) (0,60; p<0,05).

We did not find the clinical criterion value of the AOFAS with the SPF, with the relation of SPF/PPF, Area and Pressure in fractured foot (Graph 5).

DISCUSSION

Concern the age, sex, mechanism of trauma, our cause is compared to the one in the literature^{(1,9,13,18,20,22,26,27)}. About the fractured side, it is drawn to only two cases of bilateralis intra-articular fracture, however in the set of publications^{(1,9,,13,15,18,19,22,27)} there is usually higher number of bilateralis fractures.

The approach via used was the lateral one, chosen by most of the authors^{(1,2,9,13,20,22,23)}, despite some authors using the medialis⁽⁹⁾, and the laterallis and medialis approaches^(8,10,15), In 1997 Fernandes⁽⁵⁾, one of us, described the use of the anterior approach, on the shaft of the tarsus , and its advantages due to smaller incision, having less risk of necroses of the skin and no severity with the peroneal tendons⁽⁵⁾.

The use of transplant , made in only one of the cases, is another controversy, being prescribed by some physicians^{(1,2,9,13,19)} and not by others^{(18,20,22,23,27)} It is believable the authologue transplants does not increase the syntheses stability, it does not improve the final results but increase the hospital infection, and a surgical injury..

The quantity of injuries associated with the described cases (36%) and their location (the lower limbs and vertebras fractures) are compared with big part of the literature, which shows percentage ranging from 27% to 61,2% ^{(9,13,18,19,22)}.

The complications found in the sample of this study were also in accordance with the Literature. Osteomyelitis and the loss of reduction observed are frequently found in the literature^{(1,2,6,9,18,22,26)} such as the compartimentation^(14,17) syndrome. Several authors appoint to the complications related to surgical injuries^{(1,2,9,13,15,18,22,26,27)}.

Concern the clinical evaluation under the AOFAS criterion of, our sample showed average value of 75.5 (±13.35) points, value approximately found for Infant et al⁽⁶⁾ of 78 points. According to this author this index shows there were good functional results, make it possible the patient come back to their activities. Our sample shows AOFAS value criterion, also similar to the ones found for Sanders et al.⁽²³⁾, Zwipp et al.⁽²⁷⁾, Bezes et al.⁽²⁾, Melcher et al.⁽¹³⁾, and among us Pimenta and Kojima⁽¹⁹⁾ and Moraes Filho et al. ⁽¹⁵⁾.

The Axial computerized Tomography evaluation under Sanders classification also had its distributions compared to the set of Sanders et al.⁽²³⁾, and Moraes Filho et al.⁽¹⁵⁾, with the dominance of the fracture type II on type three, which had dominance on type IV.

The pre-operatory radiography evaluation under the Essex –Lopresti classification had his distribution compared to the one in the literature^(9,13,15,19) showing the joint depression type on the tongue type.

The angle of Gissane after the surgical fracture reduction showed correlation with the Second Peak of Force of the fractured feet. According with the increasing of the angle of Gissane, close to the normal one, there was an important increase in the variance of the Second Peak of Force, indicating higher impulsion with the forefoot, with no correlation with the First Peak of Force area and pressure of the rearfoot and forefoot fractures.

The clinical criterion AOFAS shoed important correlation with the first peak of force (FPF). As higher is the figure in the AOFAS criterion , the FPF was higher too, with no relation with the Second Peak of Force, neither relation with the (SPF/FPF), Area and Pressure of the fractured rearfoot. Fernandes⁽⁵⁾, studied 33 patients and 38 intra-articular calcaneal fractures , II and III by Sanders, with at least 24 months followed up, he found correlation with the angle of Böhler and AOFAS criterion⁽⁵⁾.

While analyzing the gait and the plantar pressure distribution we observed the patients showed the contact area reduced in the forefoot fractured side. As well as important values of the Peak of Force and the average Pressure in this area. This datum proves the deficit transference of weight to the anterior area of the foot. We observed in the fractured feet overload of rearfeet, probably because of the limited movement of the sub-tallar and tibial-tarsus articulation showing weakness of the sural triceps, leading to a deficit in the impulsion.

The clinical criteron evaluation used, AOFAS, showed important correlation with the values of the First Peak of Force (FPF), indicating the patients with better clinical conditions showed higher indexes in the FPF. The pathological gait often shows asymmetry of force, reduction of intervals in the curves of force in relation of the ground, considering the anomalous behavior of the vertical force , which can be an expressive muscular uncontrolled of the patient.

The Pressure Center analyses (COP) showed that the fractured foot, the trajectory was shorter. The COP presented three different behaviors: displacement until the area of the first and second head of the metatarsal, displacement till the median foot and displacement of COP not coming from the rearfoot. The normal trajectory of the Pressure Center till hallux^(3,12). The patients with calcaneals fracture did not show the normal COP displacement, decreasing then, the forces of impulsion during the gait, with the reduction of the Area of Contact in the forefoot region and increase of the Pressure of Force in the rearfoot region. It is important to emphasize it was expected the patient, with the reflex protection minimized the loads on the injury surface. However, we observed these patients showed an increasing of the gait parameters, as the Pressure of Force on the fracture, is due to the loss of functional mobility of the complexity of the ankle-foot in the post-operatory.

New perspectives of evaluation and the calcaneals fracture treatment showed it is not enough that the patient comes back to walk, but the pattern to be obtained is a relevant factor to the quality of life of this patient.

CONCLUSION

Clinically the results of the surgical results of the intra-articular calcaneals fractures were satisfactory, reaching the average of 75.5 points, under the AOFAS criterion. The surgical reduction of calcaneal fractures were satisfactory in the reconstruction angle of Böhler and Gissane. With the plantygrams of Pressure, important difference was observed between the variability: The Contact Area, Average Pressure and the Force were higher in the rearfoot than in the forefoot of the fractured calcaneal side.

REFERÊNCIAS BIBLIOGRÁFICAS

Work performed at the Hospital Governador Celso Ramos-Florianópolis- SC and Biomechanical Department of The State University of Santa Catarina – SC.

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Publication Dates

• Publication in this collection
  16 June 2004
• Date of issue
  June 2004

History

• Accepted
  09 Apr 2004
• Received
  18 Oct 2003