



ORIGINAL ARTICLE 

Year : 2020  Volume
: 19
 Issue : 1  Page : 3238 

The morphometric analysis of the patella from the male cadaveric native knees of the ethnic Igbos of Southeast Nigeria and its implications in total knee replacement
Amechi Uchenna Katchy^{1}, Augustine Uche Agu^{1}, Ikenna Theophilus Ikele^{1}, Chioma Nneka Ikele^{2}, Augustus Uchenna Ugwu^{1}
^{1} Department of Anatomy, University of Nigeria, Enugu Campus, Enugu, Nigeria ^{2} Department of Medical Rehabilitation, University of Nigeria, Enugu Campus, Enugu, Nigeria
Date of Submission  20Apr2020 
Date of Acceptance  10May2020 
Date of Web Publication  23Jul2020 
Correspondence Address: Dr. Augustine Uche Agu Department of Anatomy, University of Nigeria, Enugu Campus, Enugu Nigeria
Source of Support: None, Conflict of Interest: None
DOI: 10.4103/njot.njot_9_20
Background: In forensic study, the importance of the patellar morphometry for human identification has been widely accepted, and it also plays a role in the biomechanics of the knee. Aim: The aim of this study is to analyse the morphometric parameters of patella from the cadaver of the Igbo population of Southeast Nigeria. Materials and Methods: Parameters from 60 patellae from 30 male cadavers at the museum of the Department of Anatomy University of Nigeria were measured using the Vernier calipers. Results: The determined values of the parameters of the cadaveric knees in centimetres are as follows: PH: M =4.6, SD = 0. 47, PW: M =4.69, SD = 0.29, PT: M =2.66, SD = 0.15, PLH: M = 6.67, SD = 0.67, PLW: M = 2.86, SD = 0.27, WMAF: M = 2.55, SD = 0.18, WLAF: M =2.77, SD = 0.18. The results of the independent sample ttests indicated that there were no statistically significant differences in the mean values of the parameters of interest between the left and right patella. The result of the Pearson correlations between PH and other parameters indicated there was a very strong positive significant correlation with PW: (r[60] =0.924, P < 0.01), the PW had a strong positive significant correlation with PT (r[60] = 701, P < 0.001), WMAF (r[60] = 763, P < 0.01), and WLAF (r[60] = 700, P < 0.001). The PT had a weak significant positive correlation with PLW (r[60] = 0.338, P = 0.008) and WMAF (r[60] =0.479, P < 0.001). The PLW was weakly significantly positive correlated with WMAF (r[60] = 0.486, P < 0.001) and WLAF (r[60] = 0.403, P = 0.001). The WLAF was strongly significantly positive correlated with WMAF (r[60] = 0.975, P = 0.001). The PH among the Igbo population (M = 4.61, SD = 4.7) was significantly higher than that of Koreans (t[59] = 2.543, P = 0.014) with a small effect size (Cohen's d = 0.33). The PT among the Igbo population (M = 2.66, SD = 0.15) was significantly higher than Korea (t[59] = 22.278, P < 0.01) with a large effect size (Cohen's d = 2.88). Conclusion: This study has established that there are differences with the parameters of interest Igbo ethnic group with that of other populations of interest. The determined values will serve as a guide in the selection of patella component sizes among the studied population.
Keywords: Patella morphometry ethnic Igbos, South East Nigeria, Total knee replacement
How to cite this article: Katchy AU, Agu AU, Ikele IT, Ikele CN, Ugwu AU. The morphometric analysis of the patella from the male cadaveric native knees of the ethnic Igbos of Southeast Nigeria and its implications in total knee replacement. Niger J Orthop Trauma 2020;19:328 
How to cite this URL: Katchy AU, Agu AU, Ikele IT, Ikele CN, Ugwu AU. The morphometric analysis of the patella from the male cadaveric native knees of the ethnic Igbos of Southeast Nigeria and its implications in total knee replacement. Niger J Orthop Trauma [serial online] 2020 [cited 2023 Dec 11];19:328. Available from: https://www.njotonline.org/text.asp?2020/19/1/32/290559 
Introduction   
The patella is a seasamoid bone which is an important component of the extensor apparatus mechanism of the knee. It increases the lever arm of the extensor apparatus, thereby contributing a 50% increase on the quadriceps strength.^{[1]} The study of the patella parameters is on the increase taken into consideration the fact that it expands the knowledge of knee biomechanics and the physiopathology of knee ailments and their respective treatments.^{[2]}
In forensic study, the importance of the patellar morphometry for human identification has been widely accepted, and it also plays a role in the mechanical design of the knee. In implant design and certain surgical procedures such as patella resurfacing for total knee arthroplasty measurements of the patella and patellar ligament are often used. The harvesting technique of patellar ligament grafts during the reconstruction of the anterior cruciate ligament/posterior cruciate ligament depends on the morphometry of the donor patella.^{[3],[4],[5]}
The patella plays an important role in the stability of the native knee joint. The medial border of the most distal part of vastus medialis has transverse fibres that are directly attached to the patella. The natural tendency to lateral displacement is counteracted by the pull of these transverse fibres medially.
Therefore, the patella is of great clinical importance from the anatomical and surgical point of view. Consequently, any deviation in the morphometry of the patella bone in respect to femoral and tibial shafts may change the biomechanics of the patellofemoral joint. Many studies^{[6],[7],[8]} have confirmed ethnic and racial variations of the patella morphometry. Radiographic technique has been used to calculate the Insall–Salvati index which is defined as the ratio of the length of the patellar ligament to the greatest length of the patella by Philips et al.^{[9],[10],[11]} The limitations of using the Insall–Salvati Index include a lack of sensitivity to patella morphology and abnormalities. In addition, approximated measurements are derived from the lateral radiographs of the knee.^{[12],[13]} The authors^{[13],[14]} have made attempts to reduce the errors from the measurement on radiographs, but the approximation and assumptions which are used affect the accuracy of this radiographic technique. Consequently, measurements carried out in cadavers are likely to be more accurate because they do not involve approximation and assumptions. There is no documented study on the indices of patella morphometry of the Igbos of the Southeast Nigeria. What are the parameters of these indices? Is there any laterality in these parameters? Are there any differences in the parameters of the patella geometry of the ethnic Igbos and that of other known populations? Do these parameters correlate among themselves? This study has hypothesised that there are no differences with the parameters interest with that of other populations of interest, no correlations and no laterality among these parameters.
Therefore, the aim of this study is to determine the morphometric indices and laterality of patella from the cadaver of the Igbo population, correlate them among themselves and compare them with that of other selected populations.
Materials and Methods   
A 15cm incision on the medial sides of both knees of the cadaver [Figure 1] after which the skin and fascia lata covering both knees were carefully dissected to expose the quadriceps tendon, the patella and the patellar ligament. The tendon of quadriceps femoris and the patellar ligament were carefully freed from the underlying structures without causing any damage or alteration to the desired structures. With the knee flexed as much as possible but not in excess of 45 degrees, using a Vernier calipers the following measurements were taken from these end points:  Figure 1: Knee incision that provided access to the patella after dissection
Click here to view 
 Patella height (PH) – Linear distance between the superior border and the apex [Figure 2]
 Patella width (PW) – Linear distance between the medial and the lateral border [Figure 3]
 Patella thickness (PT) – Linear distance between the anterior surface and the median ridge on the posterior surface [Figure 4]
 Patellar ligament height (PLH) – Linear distance between the apex of the patella and the tibial tuberosity [Figure 5]
 Patellar ligament width (proximal end) (PLW) – Maximum width of the patella at approximately 1 cm from the apex of the patella [Figure 6]
 Width of medial articular facet (WMAF) – Maximum width from the medial border to the median ridge [Figure 7]
 Width of lateral articular facet (WLAF) – Maximum width from the lateral border to the median ridge [Figure 8].
Statistical analysis
We used the IBM SPSS package (IBM Corp., IBM SPSS Statistics for Windows, Version 25.0, Armonk, NY, USA) developed by International Business Machines Corporation (IBM) was used to analyse our data. Descriptive statistics were calculated for all the variables of interest. Continuous measures were summarised as means and standard deviations. The P values for comparing the means of continuous variables were determined after selecting a level of significance (α = 0.05). A one sample ttest was used for the comparison with of other selected populations. The Pearson correlation coefficient was used to determine the correlation between the knee parameters.
Results   
Descriptive statistics
The determined values of the parameters of the cadaveric knees in centimetres are as follows: PH: M = 4.6, SD = 0. 47, PW: M = 4.69, SD = 0.29, PT: M = 2.66, SD = 0.15, PLH: M = 6.67, SD = 0.67, PLW: M = 2.86, SD = 0.27, WMAF: M = 2.55, SD = 0.18, WLAF: M = 2.77, SD = 0.18 [Table 1].  Table 1: Descriptive statistics for mean parameters of the cadaveric patella from the knees of ethnic Igbos
Click here to view 
Independent samples ttest for side comparison for the patella parameters
An independent ttest was carried out to compare the parameters on both sides. The results of the independent sample ttests indicated that there were not significant differences in parameters between the left and right patella for the following parameters PH: (t[58] = 0.110, P = 0.913), PW: (t[58] =0.178, P = 0.859), PT: (t[58] = 0.170, P = 0.866), PLH: (t[58] = 0.000, P = 0.1.000), PLW: (t[58] = 0.096, P = 0.924), WMAF: (t[58] = 0.288, P = 0.774), WLAF: (t[58] =0.284, P = 0.777) [Table 2]. The test provided evidence to fail to reject the null hypothesis which stated that the means of the parameters were equal.  Table 2: Independent samples test for laterality comparison of the patella parameters
Click here to view 
Correlations among the patella parameters
The result of the Pearson correlations between PH and other parameters [Table 3] indicated there was a very strong positive significant correlation with PW: (r[60] = 0.924, P < 0.01), strong positive significant correlations with PT (r[60] = 0.797, P < 0.01) and WMAF (r[60] = 0.713, P < 0.01) and a moderate positive significant correlation with WLAF (r[60] = 0.653, P < 0.01). It had a weak positive correlation with PLW (r[60] = 0.432, P = 0.001). It had a negative weak correlation with PLH (r[60] = −0.321, P = 0.012).
The PW had a strong positive significant correlation with PT (r[60] = 701, P < 0.001), WMAF (r[60] = 763, P < 0.01), and WLAF (r[60] = 700, P < 0.001). It had a negative weak significant correlation with PLH (r[60] = −0.398, P = 0.002), and a weak positive significant correlation with PLW (r[60] = 335, P = 0.009). The PT had a weak significant positive correlation with PLW (r[60] = 0.338, P = 0.008), WMAF (r[60] = 0.479, P < 0.001), and WLAF (r[60] = 0.425, P = 0.001). The PLH was weakly significantly positive correlated to WMAF (r[60] = 0.491, P < 0.001), and WLAF (r[60] = 0.482, P < 0.001).
The PLW was weakly significantly positive correlated with WMAF (r[60] = 0.486, P < 0.001), and WLAF (r[60] = 0.403, P = 0.001).
The WLAF was strongly significantly positive correlated with WMAF (r[60] = 0.975, P = 0.001).
Onesample ttest for the mean comparison of the mean parameters of the cadaveric patella from the knees of ethnic Igbos with the mean parameters of other ethnic groups for patella height dimensions
The PH among the Igbo population (M = 4.61, SD = 4.7) was significantly higher than Korea (t[59] = 2.543, P = 0.014) with a small effect size (Cohen's d = 0.33), London (t[59] = 19.626, P < 0.01) with a large effect size (Cohen's d = 2.53), and South African populations (t[59] =4.036, P < 0.01) with a medium effect size (Cohen's d = 0.52). It was significantly lower when compared with the Finland population t[59] = −13.711, P < 0.01) with a large effect size (Cohen's d = 1.77) [Table 4].  Table 4: Onesample test mean comparison of mean parameters of the cadaveric patella from the knees of ethnic Igbos with other ethnic groups for patella height dimensions (patella height)
Click here to view 
Onesample ttest for the mean comparison of the mean parameters of the cadaveric patella from the knees of ethnic Igbos with the mean parameters of other ethnic groups for patella height dimensions
The PT among the Igbo population (M = 2.66, SD = 0.15) was significantly higher than Korea (t[59] = 22.278, P < 0.01) with a large effect size (Cohen's d = 2.88), London t (59) = 21.764, P < 0.01) with a large effect size (Cohen's d = 2.80) and USA populations t (59) = 20.736, P < 0.01) with a large effect size (Cohen's d = 1.81) [Table 5].  Table 5: Onesample ttest for mean comparison of the mean parameters of the cadaveric patella from the knees of ethnic igbos with the mean parameters of other ethnic groups for patella height dimensions (patella thickness)
Click here to view 
Discussion   
There has been an attempt by the researchers in previous studies to obtain the parameters of the patella, the articular facets of the patella and the patellar ligaments during total knee arthroplasty^{[14],[15]} as well as the use of radiographs.^{[16],[17]} Unlike the measurements from total knee replacements and radiographs, this cadaveric study had an advantage of allowing several measurements to be taken on each cadaver in situ though some authors^{[18]} had argued that shrinkage of soft tissue in embalmed samples could be a disadvantage of this method. However, some studies have demonstrated that in the contrary that the extent of shrinkage in a formalinfixed soft tissue is minimal and therefore constitutes no disadvantage.^{[19],[20]}
This study was carried out to determine the morphometric indices and laterality of patella from the cadaver of the Igbo population correlate them among themselves and compare them with that of other selected populations.
These determined parameters no doubt will be of immense benefit to the manufactures of prosthesis who had based their sizes on the Western parameters^{[21],[22]} which may not be suitable for the Igbo population.
There was no statistically significant difference in parameters between the left and right patella.
This is in consonant with other previous studies.^{[23],[24],[25]}
The PH among the Igbo population was significantly higher than that of Koreans with a small effect size. This is in consonance with the findings of Kim et al. who found in their study of Korean population a smaller patella when compared with that of the Western population. However, in comparison with that of the London and South African populations with a large and medium effect sizes, respectively. This is at variance with the findings of Hoaglund and Low^{[26]} who had postulated that generally that Caucasian knees are generally larger than Asian knees. It was significantly lower when compared with the Finland population with a large effect size. The patellar height is taken into consideration and it is of fundamental importance when evaluating patella femoral complaints, operations involving knee arthroplasty, anterior cruciate ligament, or proximal tibial osteotomy.^{[27]}
Most of these parameters correlated strongly with themselves. During TKR, the decision whether to resurface a patella or not rests with the surgeon. Apart from surgical training and experience, a preoperative analysis of patellofemoral tracking, and an intraoperative analysis of the patella femoral articular surface and articulation are also critical to the final decision. These correlations established in this study will be of immense benefits when dealing with patients of Igbo ethnic group. However, these immense benefits as stated earlier is limited by the inability of the study to provide enough information to answer all the research questions taken the sample size and sex distribution (male only) into consideration.
Conclusion   
This study has established that there are differences with the parameters of interest Igbo ethnic group with that of other selected populations of interest. The study established correlations that would be taken into consideration during the resurfacing of patella in TKR. There was no laterality among these parameters.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References   
1.  Rogers BA, ThorntonBott P, Cannon SR, Briggs TW. Interobserver variation in the measurement of patellar height after total knee arthroplasty. J Bone Joint Surg Br 2006;88:4848. 
2.  Gracitelli GC, Pierami R, Tonelli TA, Falótico GG, Silva FD, Gilberto YN, et al. Assessment of patellar height measurement methods from digital radiography. Rev Bras Ortop 2012;47:21013. 
3.  Biswas S, Sharma S. Morphometric Study of Patellar Measurement: An Overview from Eastern Zone of India. Int J Contemp Med Res2019;6:57. 
4.  Potage D, Duparc F, D'Utruy A, Courage O, Roussignol X. Mapping the quadriceps tendon: An anatomic and morphometric study to guide tendon harvesting. Surg Radiol Anat 2015;37:10637. 
5.  Yoo JH, Yi SR, Kim JH. The geometry of patella and patellar tendon measured on knee MRI. Surg Radiol Anat 2007;29:6238. 
6.  Kim TK, Chung BJ, Kang YG, Chang CB, Seong SC. Clinical implications of anthropometric patellar dimensions for TKA in Asians. Clin Orthop Relat Res 2009;467:100714. 
7.  Vaidya SV, Ranawat CS, Aroojis A, Laud NS. Anthropometric measurements to design total knee prostheses for the Indian population. J Arthroplasty 2000;15:7985. 
8.  Uehara K, Kadoya Y, Kobayashi A, Ohashi H, Yamano Y. Anthropometry of the proximal tibia to design a total knee prosthesis for the Japanese population. J Arthroplasty 2002;17:102832. 
9.  Schlenzka D, Schwesinger G. The height of the patella: An anatomical study. Eur J Radiol 1990;11:1921. 
10.  Phillips CL, Silver DA, Schranz PJ, Mandalia V. The measurement of patellar height: A review of the methods of imaging. J Bone Joint Surg Br 2010;92:104553. 
11.  Portner O, Pakzad H. The evaluation of patellar height: A simple method. J Bone Joint Surg Am 2011;93:7380. 
12.  Grelsamer RP, Meadows S. The modified InsallSalvati ratio for assessment of patellar height. Clin Orthop Relat Res 1992;282:1706. 
13.  Basso O, Johnson DP, Amis AA. The anatomy of the patellar tendon. Knee Surg Sports Traumatol Arthrosc 2001;9:25. 
14.  Iranpour F, Merican AM, Amis AA, Cobb JP. The width: thickness ratio of the patella: An aid in knee arthroplasty. Clin Orthop Relat Res 2008;466:1198203. 
15.  Baldwin JL, House K. Anatomical dimensions of the patella measured during total knee arthroplasty. J Arthroplasty 2005;20:2507. 
16.  Fucentese SF, von Roll A, Koch PP, Epari DR, Fuchs B, Schottle PB. The patella morphology in trochlear dysplasiaa comparative MRI study. Knee 2006;13:14550. 
17.  Roberts CS, King DH, Goldsmith LJ. A statistical analysis of the accuracy of sonography of the patellar tendon. Arthroscopy 1999;15:38891. 
18.  Olateju OI, Philander I, Bidmos MA. Morphometric analysis of the patella and patellar ligament of South Africans of European ancestry. S Afr J Sci 2013;109910. 
19.  Hopwood D. Fixation and fixatives. In: Bancroft JD, Stevens A, editors. Theory and Practice of Histological Techniques. London: Churchill Livingstone; 1982. p. 2040. 
20.  Boonstra H, Oosterhuis JW, Oosterhuis AM, Fleuren GJ. Cervical tissue shrinkage by formaldehyde fixation, paraffin wax embedding, section cutting and mounting. Virchows Arch (PatholAnat) 1983;402:195201. 
21.  Peng S, Linan Z, Zengtao H, Xueling B, Xin Y, Zhaobin X, Xu H. Morphometric measurement of the patella on 3D model reconstructed from CT scan images for the southern Chinese population. Chin Med J 2014;127:96101. 
22.  Vaidya SV, Ranawat CS, Aroojis A, Laud NS. Anthropometric measurements to design total knee prostheses for the Indian population. J Arthroplasty 2000;15:7985. 
23.  Ho WP, Cheng CK, Liau JJ. Morphometrical measurements of resected surface of femurs in Chinese knees: Correlation to the sizing of current femoral implants. Knee 2006;13:124. 
24.  Lim HC, Bae JH, Yoon JY, Kim SJ, Kim JG, Lee JM. Gender differences of the morphology of the distal femur and proximal tibia in a Korean population. Knee 2013;20:2630. 
25.  Murugan M, Ambika S, Nim VK. Knee cap: A morphometric study. Int J Anat Res 2017;5:355659. 
26.  Hoaglund F, Low WD. Anatomy of the femoral neck and head, with comparative data from Caucasians and Hong Kong Chinese. Clin Orthop Relat Res 1980;(152):106. 
27.  Christian B, Alexandre Z, Rodrigo P, Eduardo B, Naasson C. Comparative evaluation of patellar height methods in the Brazilian population. Revista Brasileira De Ortopedia 2016;1:537.] 
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]
