The fibular notch: an anatomical study

The morphometry of distal tibia and posterior malleolus and its clinical implications in total ankle prosthesis

PURPOSE

The aim of this study is to reveal the morphometry of the distal tibia and posterior malleolus and to generate morphometric reference data for the tibial component of total ankle prosthesis.

METHODS

This study was performed on 121 human dry tibiae (47 right, 74 left). The morphometric measurements of distal tibial structures, tibial length and the distance between the medial and posterior malleolus were measured in this study. Measurements on 44 tibiae were repeated three times and averaged for minimizing intra-observer error.

RESULTS

The tibial length was found 34.19 ± 2.31 cm. Mean values of width of fibular notch at tibial plafond and 10 mm proximal to the tibial plafond were 25.71 ± 2.44 mm and 17.81 ± 2.46 mm, respectively. Mean depth of fibular notch at tibial plafond and 10 mm proximal to the tibial plafond were 3.60 ± 1.04 mm and 3.37 ± 1.24 mm, respectively. Mean height of fibular notch was found 48.21 ± 10.51 mm. Mean width and height of medial malleolus were 25.08 ± 2.13 mm and 14.73 ± 1.85 mm, respectively. Mean width and length of tibial plafond were 27.71 ± 2.74 mm and 26.96 ± 2.62 mm, respectively. Mean values of width and height of posterior malleolus were measured 21.41 ± 3.26 mm and 6.74 ± 1.56 mm, respectively. Mean distance between medial and posterior malleolus was found 37.17 ± 3.53 mm. Mean width and depth of malleolar groove were 10.26 ± 1.84 mm and 1.73 ± 0.75 mm, respectively. The mean intra-class correlation values were found between the 0.959 and 0.999.

CONCLUSIONS

Knowing the distal tibial morphometry is crucial for designing convenient ankle replacement implants for Turkish population. To our knowledge, this study is the first in the literature that identifies posterior malleolar morphometry on dry tibiae. We believe that this study will make a significant contribution to the literature about distal tibial morphometry and especially the posterior malleolus and the data of our study can be used for designing total ankle prosthesis in Turkish population.

Fibular notch morphometry and its clinical importance on dry bones

The aim of the present study was to determine the morphometric characteristics of the fibular notch (FN). This study was carried out with 76 dry adult tibial bone specimens (right 38, left 38) with unknown age and sex collected from the Department of Anatomy, Cukurova University, Adana. The mean width of the FN was 23.04 ± 2.02 mm; the mean depth of the FN 3.63 ± 0.83 mm; the mean height of the FN was 41.76 ± 4.01 mm. The mean anterior facet length and posterior facet length was found to be 10.44 ± 1.94 mm and 13.93 ±1.63 mm, respectively. The mean value of the angle between the anterior and posterior facets was found to be 140.56° ± 11.72. The mean value of the angle between the anterior surface of the tibia and the intertubercular line was 75.5° ± 5.47. No statistically significant differences were detected between the right and left sides for all measurements. It is considered that knowing the morphometric and anatomical characteristics of the fibular notch in detail will help radiologists evaluate the talocrural region. It is also considered that these data will guide surgeons and help determine the appropriate size for ankle reconstruction operations.

Injury to the posterior malleolus in Maisonneuve fractures

PURPOSE

The aim of this study was to describe the incidence and a complex pathoanatomy of posterior malleolus fractures in a Maisonneuve fracture.

METHODS

The study included 100 prospectively collected patients with a complete clinical and radiological documentation of an ankle fracture or fracture-dislocation including a fracture of the proximal quarter of the fibula.

RESULTS

A posterior malleolus fracture was identified in 74 patients, and in 27% of these cases it carried more than one quarter of the fibular notch. Displacement of the posterior fragment by more than 2 mm was shown by scans in 72% of cases. Small intercalary fragments were identified in 43% of cases. Fractures of the Tillaux-Chaput tubercle were identified in 20 patients.

CONCLUSION

Our study has proved a high rate of posterior malleolus fractures associated with a Maisonneuve fracture, and documented their considerable variability in terms of involvement of the fibular notch, tibiotalar contact area, direction of displacement and frequency of intercalary fragments. Of no less importance is a combination of Tillaux-Chaput fractures with a Maisonneuve fracture.

In Different Gender Groups, What Is the Impact of the Fibular Notch on the Severity of High Ankle Sprain: A Retrospective Study of 360 Cases

OBJECTIVES

The role of the distal tibiofibular ligament in the occurrence of high ankle sprain (HAS) has been widely studied. But previous studies have overlooked the physiological and anatomical differences between males and females and have not further refined gender. Therefore, the impact of the anatomical morphology of fibular notch (FN) on HAS in different genders is still unclear. This study aimed to explore the impact of different types of FN on the severity of HAS and to estimate the prognosis of patients with HAS while excluding anatomical differences caused by gender.

METHODS

One hundred and eighty patients with HAS were included in this study as the experimental group (i.e., HAS group). They were further divided into four groups according to gender and FN depth, with deep concave FN ≥ 4 mm and shallow flat FN < 4 mm. Another 180 normal individuals were set as the control group. The FN morphological indicators, tibiofibular distance (TFD), and ankle mortise indexes were measured and compared with those in HAS group. The independent t-test was used to compare continuous variables between groups, the intraclass correlation coefficient (ICC) was used to analyze the reliability of intra-observer measurement, and the Pearson correlation coefficient was used to verify the correlation between FN and the severity of HAS.

RESULTS

In males with shallow flat type, the measurements of anterior tibiofibular distance (aTFD), middle tibiofibular distance (mTFD), posterior tibiofibular distance (pTFD), front ankle mortise width (fAMW), middle ankle mortise width (mAMW), posterior ankle mortise width (pAMW), and depth of ankle mortise (DOAM) in HAS group were significantly larger than those in normal group (p < 0.05). In male patients with deep concave type, the measurements of aTFD, mTFD, fAMW, mAMW, and DOAM were significantly larger than those in normal group (p < 0.05). Among female patients with shallow flat type, the measurements of aTFD, mTFD, pTFD, fAMW, mAMW, pAMW, and DOAM were found to be significantly larger than those in normal group (p < 0.05). Among female patients with deep concave type, the measurements of mTFD, pTFD, fAMW, mAMW, and DOAM were found to be significantly larger than those of the normal group (p < 0.05). The depth of FN was negatively correlated with TFD, and the AOFAS score of patients with shallow flat type was significantly lower than that of patients with deep concave type after treatment (p < 0.05).

CONCLUSIONS

In different gender groups, compared with the normal controls, the TFD and partial ankle mortise indices were significantly different in HAS patients. Moreover, FN depth was negatively correlated with TFD, and the AOFAS score of shallow flat patients was significantly lower than that of deep concave patients. These suggested that shallow flat FN may be associated with more severe distal tibiofibular ligament injury and ankle mortise widening, leading to poorer prognosis. This should be taken seriously in clinical practice.

The safe zone of distal fibula was determined based on the classification of lateral malleolus fossa

BACKGROUND

Lateral malleolus fractures are very common, and the distal fibular geometry is complex. This study aimed to classify the lateral malleolus fossa (MF) into different types by characterizing the lateral MF imaging morphology and exploring the relationship between the lateral MF and internal fixation position after distal fibula fractures.

METHODS

Anteroposterior CT reconstruction was performed on 248 subjects. After reconstruction, the deepest point of the lateral MF was located, and then, the cross-sectional shape of the lateral MF was observed and classified.

RESULTS

According to the morphology of the CT cross section, the lateral MF was divided into three types: type C (43.1%), type V (32.2%), and type Flat (24.7%). Type V (3.98 ± 0.82) was significantly longer than type C(2.83 ± 0.54) and type Flat (1.84 ± 0.42) in cd. Similarly, in ∠α, Type Flat(136.31 ± 9.63) was the largest, followed by type C (116.51 ± 8.79), and type V (89.31 ± 9.07) was the smallest. Other measurements were not found any significant differences between the above.

CONCLUSION

According to the morphology of the CT cross section, the lateral MF was divided into three types: type C, type V and type Flat. Type V is most likely to be invaded when fixing the distal fibula. Screws less than 9 mm should be selected when fixing, and screws no more than 10 mm should be selected when there are type C and type Flat of MF.

Lateral malleolar crest and its clinical importance

PURPOSE

During study of anatomy of a fractured posterior malleolus of the ankle on CT scans, the authors noticed a prominent crest on the lateral malleolus, which they termed the lateral malleolar crest (LMC). As, in their view, LMC is a clinically important structure which was only briefly mentioned by a few authors without an official term, they focused on the anatomy of this structure.

MATERIALS AND METHODS

A total of 352 dry fibulae were analyzed and the following parameters recorded: (F) length of the fibula, (LMC) total length of LMC, (A) length of the part of the examined crest from the superior border of the articular facet of the lateral malleolus (AFLM) to its most proximal intersection with the midline of the fibula, (B) height of the medial triangular rough surface, and (A/F) A/F ratio.

RESULTS

The crest was observed in all specimens. (F) was 346.5 ± 26 mm (95% confidence interval [CI] 344-349), (LMC) was 85.4 ± 11.6 mm (95% CI 84.2-86.6), (A/F) was 25% ± 3% (95% CI 24.7-25.3) in the whole group. (A) was 25.9 ± 6.5 mm (95% CI 24.8-26.8) in the whole group, (B) was 34.9 ± 4.7 mm (95% CI 34.3-35.5) in the whole group, 36 ± 6.1 mm (95% CI 35.1-36.9).

CONCLUSION

LMC is an important structure on the lateral malleolus. The knowledge of its anatomy is essential for placement of syndesmotic screws or/and the fibular plate.

Defining the fit and ideal entry site of the fibula rod system--a computed tomography based study in elderly patients with lower limb infections, vascular diseases or tumors

OBJECTIVES

To determine the configuration of the distal fibula anatomy and the fitness of the Fibula Rod System (Acumed®, Hillsboro, Oregon) in a series of fibula models and to determine the optimal entry site of the rod.

METHODS

Consecutive series of computed tomography (CT) of tibias and fibulae with no fracture or deformity were converted to stereo-lithograph format, and imported into Meshmixer software (Autodesk, San Rafael, California). A 3.6 × 180 mm fibula rod model was virtually inserted to best fit the intramedullary canal of the fibula model and to a depth of 0 mm proud at the distal fibula. The location of the entry point in relationship to the fibular tip, and the distance between the rod and the lateral fibula cortex were measured.

RESULTS

CT of 41 fibulae (23 male and 18 female patients) contributed to the three-dimensional fibula modeling. The entry point was 3.5 mm (SD 2.0) medial to (in mortise view) and 1.0 mm (SD 2.1) anterior to (in lateral view) the fibular tip. The fibula rod was inserted to a depth of 6.2 mm (SD 2.1) proximal to the fibula tip. The mean shortest distance of the rod to the outer cortex was 1.88 mm (SD 0.87). There was a breach of the posterolateral cortex in one patient.

CONCLUSION

The guide pin entry site of fibula rod should be medial and anterior offset with reference to the fibula tip, in contrary to the distal tip as recommended in the manual. There is a chance of breaching the posterolateral cortex with rod entry.

Does the Level of Syndesmotic Screw Insertion Affect Clinical Outcome after Ankle Fractures with Syndesmotic Instability?

OBJECTIVE

Ankle fractures are often combined with syndesmotic instability, requiring reduction and stabilization. However, the optimal level for syndesmotic screw positioning remains unclear. This study aims to evaluate the effect of different syndesmotic screw insertion levels on postoperative clinical outcomes and determine whether an optimal level exists.

METHODS

This retrospective study included data from 43 adult patients with acute closed ankle fractures combined with intraoperative evidence of unstable syndesmotic injuries who underwent open reduction internal fixation from January 1, 2017 to March 1, 2018 according to the inclusion and exclusion criteria. All 43 patients were divided into three groups based on the syndesmotic screw placement level: trans-syndesmotic group: screw level of 2-3 cm; inferior-syndesmotic group: screw level <2 cm; and supra-syndesmotic group: screw level >3 cm. Clinical outcomes were measured at the final follow-up, including the American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, Olerud-Molander Ankle Score (OMAS), short-form 36-item questionnaire (SF-36), visual analogue scale (VAS) score and restrictions in ankle range of motion (ROM). The relationships between screw placement level and clinical outcomes were analyzed with the Kruskal-Wallis H-test and Spearman correlation analysis.

RESULTS

The median follow-up duration was 15 months (range, 10-22 months). No patients developed fracture nonunion or malunion or experienced hardware failure. The outcome scoring systems showed an overall score for the entire group of 94.91 points for the AOFAS ankle-hindfoot score, 83.14 for the OMAS, 96.65 for the SF-36, 1.77 for the VAS, 9.14° for the restrictions in dorsiflexion, and 1.30° for the restrictions in plantarflexion. There were no significant differences among three groups in clinical outcomes (P > 0.05). Neither the AOFAS score nor OMAS had significant correlations with screw insertion level (P = 0.825 and P = 0.585, respectively). No postoperative arthritis or widening of the tibiofibular space was observed at the final follow-up.

CONCLUSION

Different syndesmotic screw placement levels appear not to affect the clinical outcomes of ankle fractures with syndesmotic instability. No optimal level was observed in this study. Our findings suggest other clinically acceptable options apart from syndesmotic screw placement 2-3 cm above the ankle.

Maisonneuve Fractures of the Ankle: A Critical Analysis Review

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Maisonneuve fractures (MFs), originally described as subcapital (high) fibular fractures with additional injury to the anterior and interosseous tibiofibular ligaments, display a variable injury pattern, ranging from stable to highly unstable fractures.

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The high incidence of associated fractures of the posterior malleolus, the medial malleolus, and the anterolateral distal tibia (the "anterior malleolus") as well as the variable position of the fibula in the fibular notch (FN) warrant preoperative examination via computed tomography (CT).

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The main goal of treatment is anatomic reduction of the distal fibula into the FN, which requires prior reduction of displaced posterior malleolar fractures, if present, to restore the integrity of the FN.

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Open reduction of the distal fibula into the FN and fixation with 2 transsyndesmotic screws or fixation with a screw(s) and suture-button implant, under direct vision, on the lateral aspect of the ankle joint and anterior tibiofibular alignment are preferred over closed reduction to avoid sagittal or rotational malpositioning, which is associated with an inferior outcome.

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Intra- or postoperative 3D CT visualization is essential for assessment of the accuracy of the reduction of the distal fibula into the FN.

Anatomical Study of the Interosseous Ligament of the Tibiofibular Syndesmosis: An Analysis of Osseous Morphology and Attaching Interposing Structures

BACKGROUND

The morphological features of the interosseous tibiofibular area in relation to the tensile stress of the interosseous ligament (IOL) have rarely been discussed. The purpose of the present study was to investigate the IOL on the basis of osseous surface morphology and macroscopic and histological anatomy. We hypothesized that the osseous surface of the interosseous tibiofibular area has a specific feature corresponding to the fibrous structure in the IOL.

METHODS

Eighteen ankles from 15 cadavers were analyzed. Micro-computed tomography (micro-CT) images were obtained for all specimens to observe the osseous surface in the syndesmosis and to visualize the distribution of cortical bone thickness. Fifteen ankles were macroscopically analyzed, and the other 3 ankles were histologically analyzed.

RESULTS

Micro-CT imaging revealed the osseous prominence on the medial side of the fibula. Cortical thickness mapping showed that the thickness of the cortical bone on the medial side of the fibula proximal to the prominence (mean and standard deviation, 1.4 ± 0.5 mm; p < 0.001) was greater in comparison with the other quadrants, namely, the proximal part of the tibia (0.8 ± 0.2), distal part of the fibula (0.7 ± 0.2), and distal part of the tibia (0.5 ± 0.1). Macroscopic analysis indicated that the perforating branch of the fibular artery ran through the proximal top of the IOL, which formed a thickened fiber and was attached to the fibular prominence. Histological analysis revealed that the thickened fibrous part of the IOL attached to the fibula via the fibrocartilaginous insertion. At the middle of the IOL, thin and fatty-like tissue was interposed between the tibia and the fibula.

CONCLUSIONS

We observed that the osseous prominence of the fibula corresponded to the proximal thickened part of the IOL via the fibrocartilaginous attachment. The thickened proximal part of the IOL was consistently found in this location; we believe that this finding was related to the fact that the fibular artery perforated the adjacent distal part of the interosseous membrane (IOM).

CLINICAL RELEVANCE

The location of the prominence on the medial aspect of the fibula could be a helpful clue as to the ideal location of syndesmotic fixation.

The coracoglenoid notch: anatomy and clinical significance

INTRODUCTION

The superior surface of the anatomical neck is presented in the classification of scapular fractures as a 2-cm-long structure, which does not correspond to reality. This issue has not yet been adequately addressed in the literature. The aim of the study was to assess the variability of a notch between the upper rim of the glenoid and the coracoid base, the so-called coracoglenoid notch (CGN), and its clinical significance.

MATERIALS AND METHODS

The study was based on the examination of 204 dry bone specimens of adult scapulae (92 male and 112 female). We have determined quantitative criteria for the evaluation of the CGN type, measuring the offset of anatomical neck using a digital caliper. The findings were compared with 3D CT reconstructions of fractures of the scapular anatomical neck.

RESULTS

Three basic types of CGN have been identified: type A-a well-developed notch in 31%, type B-a shallow notch in 53% and type C-an absent notch in 16%. No significant difference in CGN was found between the sexes, or between the right and left sides. When compared with our six cases of the anatomical neck fracture of the scapula, two patients displayed CGN type A and type B, respectively; but in four patients, it was impossible to distinguish between types A and B.

CONCLUSION

The study has documented a high variability of CGN. Its presentation in the classification schemes does not correspond to anatomical reality. The presence of a deep, or shallow, notch may constitute an anatomical predisposition to a fracture of the anatomical neck.