|Year : 2021 | Volume
| Issue : 1 | Page : 30-34
Vascular anatomy of distal end of femur and its clinical implications
Deepa Bhat1, Sunilkumar Doddaiah2, Pushpalatha Murugesh1, NB Pushpa1
1 Department of Anatomy, JSS Medical College, JSS Academy of Higher Education and Research, Mysore, Karnataka, India
2 Department of Community Medicine, JSS Medical College, JSS Academy of Higher Education and Research, Mysore, Karnataka, India
|Date of Submission||15-Feb-2020|
|Date of Acceptance||31-Jan-2021|
|Date of Web Publication||07-Apr-2021|
Dr. Deepa Bhat
Department of Anatomy, JSS Medical College, JSS Academy of Higher Education and Research, Mysore - 570 015, Karnataka
Source of Support: None, Conflict of Interest: None
Introduction: The distal end of the femur is a highly vascular tissue with unique features in its blood supply. The outcome of surgical interventions is determined by the interference of corresponding blood supply. The study examines the pattern of blood supply in terms of density, size, and direction of vascular foramina (VF) to the distal end. Material and Methods: The lower end of normal adult dry femora (n = 300) was divided into segments. The number, size, and direction of VF in each segment were documented. Wilcoxon signed-rank test identified the statistical difference in the number of VF between various segments and Friedman test compared the difference between segments of two sides. Results: The maximum average number of VF was observed in medial condylar surface while minimum in central part of intercondylar region. Condylar medial recorded the highest number of VF of all sizes. The number of VF of >2 mm size was found to be significantly different between right and left in right condylar lateral and right intercondylar posterior regions. Right condylar lateral had considerably large number of VF of >2 mm size with statistical significance (P = 0.000). A Friedman test indicated that segements of two sides rated differently. Discussion and Conclusion: The density of VF through which vessels traverse at lower end were not only numerous but also constant and uniformly scattered. Detailed understanding of the arterial anatomy of lower end helps to identify and localize vascular pedicles, thus ensuring vitality of graft as well as donor site.
Keywords: Condyles, femur, lower end, vascular foramina, vascularity
|How to cite this article:|
Bhat D, Doddaiah S, Murugesh P, Pushpa N B. Vascular anatomy of distal end of femur and its clinical implications. J Anat Soc India 2021;70:30-4
|How to cite this URL:|
Bhat D, Doddaiah S, Murugesh P, Pushpa N B. Vascular anatomy of distal end of femur and its clinical implications. J Anat Soc India [serial online] 2021 [cited 2021 Apr 22];70:30-4. Available from: https://www.jasi.org.in/text.asp?2021/70/1/30/313163
| Introduction|| |
Femur is the longest and strongest proximal weight-bearing bone of the lower limb. It is composed of an upper end, lower end, and shaft. The distal extremity is large and massive bearing two large condyles, which articulates with the tibia consequently transmitting weight. Anteriorly the condyles are separated by smooth shallow surface, articulating with patella and posteriorly they protrude considerably with the interval between them forming a deep notch, the intercondylar fossa. The lateral condyle is protruberent and is the broader each in its anteroposterior and transverse diameters. When the femur is held perpendicular, the medial condyle is the longer and projects to a lower level. The distal end is of great importance from the anatomical, functional, and clinical point of view. It is exposed to serious morbidity as a consequence of its position, structure, and weight-bearing function.
Femur is a highly vascular with distinctive blood supply. The diseases affecting knee joint or lower end of the femur such as osteoarthritis and fractures are very common. It is additionally utilized for harvesting vascularized bone grafts. The success of surgical interventions undertaken at lower end is determined by interference by means of corresponding blood supply. Increased incidence of ischemic events at medial femoral condyle over lateral necessitates precise understanding of vascular anatomy.
The purpose of this study is to understand the pattern of blood supply to the distal end of femurthrough the density, size, and direction of its vascular foramina (VF). This would facilitate in contemplating surgical procedures at this region.
| Material and Methods|| |
The present study was undertaken on 300 dry normal adult femora obtained from the department of anatomy after obtaining the institutional ethical clearance. Among them, 150 belonged to the right side and rest to the left. Specimens were selected according to the following criteria: (1) no significant osteoarthritis or morphological changes in the lower end and (2) bone intactness.
Lower end of the femur was divided into following segments: (a) supracondylar–anterior (SCA)/supracondylar–anterior posterior (SCP); (b) condylar–medial (CM)/condylar–lateral (CL); (c) intercondylar-central/intercondylar peripheral (ICP).
The following parameters were worked out.
- The VF was identified by the presence of a well-marked groove and canal on different segments of the bone. The Kirschner (K)-wire of diameter 0.8 mm was probed through each foramen to verify their patency as well as the size. The foramina which easily admitted K-wire of 2-mm gauge was noted as A ≥2 mm, those which did not allow 0.6 mm K-wire were noted as C ≤0.5 mm, and rest as B = 0.5–2 mm [Figure 1].
|Figure 1: Measurement of VF: A = Vascular foramina easily admitting 2 mm K-wire, B = Admitting 1 mm K-wire, and C = Not admitting 0.6 mm K-wire|
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The distribution of VF in each of these segments was noted. Their number and size were counted and documented photographically.
The direction of the foramina in each segments were noted and were categorized into three types: horizontal, upper oblique, and lower oblique.
The data collected were entered into Microsoft Excel 2010, and the statistical analysis was done using the SPSS version 22. (IBM Corp. Released 2013. IBM SPSS Statistics for Windows, Version 22.0. Armonk, NY: IBM Corp). The bones were analyzed to determine if the distribution of number of VF was normal. A Wilcoxon signed-rank test was applied to find statistical difference in the number of VF between various segments of lower end of the right and left femur. Friedman test was used to compare the significance in number of VF between segments of two sides. A P < 0.05 was taken statistically significant.
| Results|| |
A total of 300 (150 right-sided and 150 left-sided) bones were evaluated in this anatomical study.
The average number of VF recorded in different segments at the lower end is shown in [Figure 2] and of different sizes in [Figure 3].
|Figure 2: Average number of vascular foramina in different segments of lower end of the femur|
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|Figure 3: Vascular foramina of various sizes in different segments of lower end of the femur|
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In the lower end, the maximum average number of VF was observed in medial condylar surface (right - 12.38, left - 12.67) and minimum in the central part of intercondylar region (right 3.23, left - 3.31).
Large-sized VF (>2 mm) was recorded in the left SCP, both left and right CM surfaces. CM recorded the highest number of VF of all sizes.
The direction of VF in the lower end documented was: horizontal - 37.89%; upper oblique - 35.77%; and lower oblique - 26.34%.
The VF on various segements of lower end are depicted in [Figure 4],[Figure 5],[Figure 6],[Figure 7],[Figure 8] (A ≥2 mm, B = 0.5–2 mm, and C ≤0.5 mm.
|Figure 4: Large, prominent vascular foramina in the intercondylar region|
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|Figure 6: Prominent but few vascular foramina on supracondylar posterior surface|
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|Figure 7: Larger density and prominent vascular foramina on lateral surface of medial condyle|
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|Figure 8: Prominent vascular foramina on lateral surface of lateral condyle|
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The Shapiro–Wilk test confirmed that the data show a nonnormal distribution of the number of VF (P = 0.000). Hence, Wilcoxon signed-rank test was applied to find statistical difference between various segments of lower end of the right and left femur. The segments between which significant difference was noted are described in [Table 1].
|Table 1: Statistical comparison of vascular foramina between various segments of right and left side|
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Right supracondylar posterior region had statistically significant difference in the number of VF of all the sizes than left. Only the number of VF of >2 mm size was found to be significantly different between right and left in the right condylar lateral and right ICP regions. Right lateral condyle had considerably large number of VF of >2 mm size with statistical significance (P = 0.000).
Friedman test test was used to compare the number of VF between segments of two sides. The results are depicted in [Table 2].
|Table 2: Comparison of the number of vascular foramina between segments of two sides|
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A Friedman test indicated that right and left lower end of the femur segments were rated differently: Chi-square (2) = 1236.490, P = 0.000 and Chi-square (2) = 1503.857, P = 0.000, respectively.
| Discussion|| |
The distal end of the femur is abundantly nourished by the branches of popliteal artery. The medial condyle is supplied by deep branch of descending genicular artery (DGA) and medial superior genicular artery (MSGA) and lateral condyle by lateral superior genicular artery (LSGA). The arteries to supracondylar region are derived from DGA, MSGA, LSGA, and intercondylar region are from middle genicular artery. Due to generous vascularity, necrosis consequent to fractures seems to be implausible. The studies associated to VF of the femur are meager and scanty literature has been added in the previous 80 years. The density of VF through which the vessels traverse at lower end were not only numerous but also constant and uniformly scattered. The findings are comparable to research by Rogers in 1953. The amplitude of blood supply to the distal end compared to proximal end of the bone has direct implications on the frequency of fractures and other traumatic injuries. Earlier study through resin injection technique has demonstrated that the vessels supplying lower end were of sufficient size to allow microvascular anastomosis (41 mm).
While harvesting the condyles for grafting, vascularity has to be taken into consideration to avoid the donor site complications. The topographic knowledge of larger VF of lower end which admits bigger vessel entry, would help the surgeon to be vigilant during graft preparation, instrumentation, and its fixation.
Distinguishing the vascular pattern around the knee from the perspective of osteotomies is critical, when considering potential complications. Zone of risk has to be precisely considered (zone of high-risk vessels <5 mm from the cut, between 5 mm and 10 mm as moderate, and more than 10 mm as no risk).
MC segment of both sides presented with the highest number of VF of all sizes and density. MC as donor site presents several exceptional features sch as length of pedicle and its diameter that is advantageous for microsurgical transfers. The compound flap at this region offers nutrition to its bony and skin portions separately, permitting various allowing multifold spatial positioning. Martin et al. demonstrated the vascular anatomy in 36 cadaveric dissections and found that the pedicle with a diameter of 1.5–3.5 mm at its origin.
Consistent scattering of VF and their larger size provides plentiful periosteal blood supply to MC allowing adequate corticocancellous bone flap harvest without jeopardizing the nutrition. The high osteogenic potential of cambium layer and density of VF makes this area an exemplary choice to combat resistant bony nonunions, irrespective of site and size. Thus, the MC is a preferred donor site for vascularized bone grafts. Being a nonweight-bearing portion with its superficial location provides a broad area of graft that can be harvested without affecting the articulation or strength of femur shaft. No donor site morbidities have been reported in any of the studies till date. In contrast, the clinico pathological studies by Ahuja and Bullough and Ashok and Robert have reported that osteonecrosis of the distal femur occurs more often in the MC than in the LC. This contradicts the assumption of safe utility of MC in graft procedures. Suitability of MC as donor site must be thoroughly evaluated for osteonecrosis due to osteoarthritis or rheumatoid arthritis, etc.,
CL had average distribution of VF of all sizes with slightly higher number of VF of >2 mm size. This is contrary to the findings of Morsy et al. on wet specimens with the VF of average diameter 1.3 mm (range 0.9–1.7 mm) and 1.2 mm (range 0.7–1.9 mm), from superficial (patellar) branch and a deep (condylar) branch, respectively. The right side showed statistically significant difference in average number of VF than left. A potentially significant difference exists between the intraosseous and extraosseous blood supply to the medial and lateral femoral condyles that may explain the higher frequency of ischemic events occurring in the MC. The intraosseous supply to the LC was shown to consist of an arcade of vessels providing multiple branches to the subchondral bone with no obvious “watershed” region of limited vascularity. The intraosseous supply to the MC is by a single nutrient vessel nourishing the subchondral bone with an obvious watershed area of limited supply. Furthermore, the proximity of the extraosseous vessels to the MC and the standard femoral tunnel used during posterior cruciate ligament reconstruction may account for the occurrence of avascular necrosis after this procedure.
Rogers' study showed that usually there are 10–15 large foramina and great numbers of smaller foramina (about 20) found in the SCA region. This number is almost similar to foramina on SCP. A few small scattered foramina were observed on the lateral and medial supracondylar region. This is similar to our study except >2 mm sized VF being denser on the right. The utility of this region is clinically correlated by the study of Doi and Sakai, who demonstrated that free vascularized thin corticoperiosteal grafts and small periosteal supracondylar grafts might be readily harvested from this region without disturbing the vascularity. This is due to better osteogenic potential and its compliance to the recipient bed configuration.
Intercondylar area exhibited VF ranging from 3 to 9 in number. The central zone had VF of larger sizes, but periphery had more of <0.5 mm size. This is different from the distribution pattern of Rogers' study that had uniform distribution of 15–25 foramina of sizes ranging from 3 to 8 mm in 22% of bones. Distinct fovea [larger VF ranging from 3 to 8 mm] were observed in the anterior inferior portion of intercondylar fossa between the attachments of cruciate ligaments in 78% of bones. Each fovea had an opening of 5–15 large foramina that extended deeper than smaller and medium-sized VF.
In addition, the density of VF at ICP associated with medial condyle is largely reduced. This could be causative cofactor for osteochondrosis dissecans. Hence, the region adjacent to the femoral insertion of the posterior cruciate ligament is the most frequent site for osteochondrosis dissecans in the knee joint. Osteotomies of the distal femur, for realigning a varus or valgus leg alignment, bleed substantially. The periosteal feeders or larger vessels near the bone cuts should be safeguarded during the procedure.
The limitations of the study would be possible damage to the VF due to prodding by students or while procuring the bone and cleaning, which could alter the dimension of the opening. The combination of cadaveric observational study with intervention through latex injection and analysis through radiographic techniques would further enhance the credibility of these findings.
| Conclusion|| |
Several attempts have been made to correlate vascular patterns with the outcome of clinical interventions at the lower end. Detailed understanding of the arterial anatomy of bones utilized for harvesting vascularized bone flaps allows identification of portions at risk. The pattern of distribution of VF at different segments of lower end affirms the nonoccurrence of osteonecrosis at the distal end. However, localization of vascular pedicles of larger size will ensure the vitality of graft as well as donor site.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
[Table 1], [Table 2]