Introduction:
The wrist is involved in many functional hand activities which exposes it to a high number of traumatic injuries and degenerative diseases. (1) Its extreme anatomical and biomechanical complexity makes it prone to wrist pathologies which pose a significant diagnostic and therapeutic challenge. (2) The advent of imaging techniques has made it easier to diagnose the disorders of the wrist and radiography is the first modality of choice preferred in the evaluation of the normal anatomy of the bony wrist structures and wrist pathologies. (3, 4) Wrist measurements based on various bony landmarks on posteroanterior (PA) and lateral wrist radiographs have been used in the calculation of carpal indices. (5) These radiological indices are commonly altered in wrist pathologies. (3) Therefore, their evaluation aids in the diagnosis, treatment, and follow-up of disease progression and assessment of the outcome of treatment. (4-6) The assessment of radiological indices is more objective and simple compared to the difficult interpretation of subtle wrist changes on radiographs. (7)
Carpal collapse is the progressive loss of carpal height associated with advancing wrist diseases such as rheumatoid arthritis, osteonecrosis of the lunate (Kienbock’s disease) and traumatic injuries to the wrist. (3, 4, 8) The assessment of the degree of carpal collapse in these conditions is important in informing their surgical management. (9) Different techniques of measuring the degree of carpal collapse have been documented. The standard accepted method is the carpal height ratio (CHR) which is measured by dividing the carpal height by the length of the 3rd metacarpal with both measurements taken in the long axis of the 3rd metacarpal. (10) However, the use of CHR is limited in cases where the entire 3rd metacarpal is not fully visualized due to technical problems such as coning down of the radiograph beam. (4, 9) Furthermore, disease processes involving the 3rd metacarpo-phalangeal joint also makes it impossible to accurately measure the length of the 3rd metacarpal. (9)
To overcome these limitations, the revised carpal height ratio (CHRr) was proposed by Nattrass et al. in 1994. (11) This ratio is determined by dividing the carpal height by the length of the capitate. The capitate is preferred due to its well-defined anatomical margins and its rare involvement in disease processes. (9) However, the accuracy of using CHRr in assessing the carpal collapse may be affected by the different shapes of the capitate and its significant gender differences. (8, 9)
The carpal height and carpal height ratio vary in different population groups. (3-5, 12, 13) These variations have been attributed to differences in sex, age-groups, race and ethnicity. (3,4) Therefore, there is need for a normal population-specific reference database which wrist pathological values can be compared with. (3, 6, 8) In unilateral wrist pathology, it is best to compare the wrist indices with the healthy side as a reference, however, this is only applicable for some parameters such as carpal angles. (7, 8) Furthermore, normal reference values are important in the assessment of bilateral wrist disease. Data regarding the carpal height ratio (CHR) and revised carpal height ratio (CHRr) in Delta State, Nigeria is scarce. This study therefore aimed at assessing the CHR and CHRr using PA wrist radiographs archived in a teaching hospital in Delta State, Nigeria.
Materials and Methods
This was a retrospective cross-sectional study carried out in the Radiology department of Delta State University Teaching Hospital, Oghara, Nigeria, after obtaining ethical approval from the Hospital’s ethics and research committee (HREC/PAN/2021/031/0341). Unpaired wrist radiographs of patients who presented between 1st January, 2014 and 31st July, 2021 with suspected hand or wrist pathology were retrieved from the Picture Archiving and Communications Systems (PACS) of the Radiology department. The inclusion criteria entailed apparently normal postero-anterior (PA) wrist radiographs of both male and female adult patients aged 18 years and above. The study excluded radiographs of patients aged below 18 years or with incomplete skeletal maturity, radiographs with evidence of previous wrist trauma or surgery, any form of arthritis (rheumatoid, post-traumatic, post-infectious, or idiopathic), or congenital anomalies of the wrist. Furthermore, radiographic views of the wrist other than the PA view were also excluded. Therefore, 135 unpaired wrist radiographs of 54 males and 81 females fit our inclusion criteria.
Linear measurements were taken on the radiographs using a digital caliper provided by PACS. The parameters were measured in cm and thereafter converted to millimeter (mm). The length of third metacarpal was measured along its longitudinal axis extending from its distal to proximal articular surfaces (Fig 1). (3) The longitudinal axis of the 3rd metacarpal was extended proximally to determine the carpal height which was measured from the base of the middle metacarpal to the distal articular surface of the radius (Fig 2). (3, 7) The capitate length was measured from its distal pole where it articulates with the 3rd metacarpal to its proximal pole at the inter-carpal joint (Fig. 3). (3, 6) The carpal height ratio (CHR) was calculated by dividing the carpal height by the length of the third metacarpal. (10) The revised carpal height ratio (CHRr) was obtained by dividing the carpal height by the length of the capitate. (11)
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Figure 1: Postero-anterior wrist radiograph showing the measurement of 3rd metacarpal length. |
Figure 2: Postero-anterior wrist radiograph showing the measurement of carpal height |
Figure 3: Postero-anterior wrist radiograph showing the measurement of capitate length |
Data were analyzed using Statistical Package for Social Sciences (SPSS) version 22. The measurements were summarized in the form of means and standard deviations. Data were classified according to gender, and 10 years' age groups namely; 21-30, 31-40, 41-50, 51-60, 61-70, 71-80, and 81-90 years. Independent t-test was used to determine the gender differences in the metric variables while the differences between the various age-groups were assessed using Analysis of variance (ANOVA). A P value less than 0.05 was considered to be statistically significant.
Results
The 135 wrist radiographs evaluated belonged to 54 males (40%), and 81 females (60%). The age of the patients ranged from 20 to 85 years with an average age of 35.13 ± 17.77 years for males and 43.86 ± 16.08
years for females. The radiographs were unpaired and comprised 62 right and 73 left wrists. Based on the 10 years’ age-group classification, majority (46,34.1%) of the radiographs belonged to patients in the 31-40 years’ age-group (Table 1).
| Table 1: Age Distribution of Patients |
Age-group (years) |
Frequency |
Percentage (%) |
21-30 |
20 |
14.8 |
31-40 |
46 |
34.1 |
41-50 |
18 |
13.3 |
51-60 |
23 |
17.0 |
61-70 |
12 |
8.9 |
| 71-80 |
13 |
9.6 |
81-90 |
3 |
2.2 |
Total |
135 |
100 |
The mean carpal height, middle metacarpal height and capitate length in the studied population were 31.77mm, 67.34mm and 23.34mm respectively (Table 2).
| Table 2: Descriptive statistics of all variables in the studied population |
| |
Minimum (mm) |
Maximum (mm) |
Mean (mm) |
Std. Deviation |
Carpal height |
26.20 |
38.50 |
31.77 |
2.63 |
Middle metacarpal height |
56.80 |
79.60 |
67.34 |
4.78 |
Capitate length |
18.10 |
28.30 |
23.34 |
2.02 |
Carpal height ratio |
0.33 |
0.63 |
0.47 |
0.04 |
Carpal height ratio revised |
1.23 |
1.58 |
1.36 |
0.07 |
These metric parameters were significantly larger in males than in females (p<0.05) (Table 3). The average carpal height ratio was 0.47±0.04 while the mean CHRr was 1.36±0.07 (Table 2). The CHR was significantly larger in males (p=0.001) while the CHRr did not show any significant association with gender (p=0.211) (Table 3).
| Table 3: Gender differences in the parameters |
Variable |
Males |
Females |
P value |
Carpal height (mm) |
33.64 ± 2.13 |
30.53 ± 2.15 |
0.001* |
Middle metacarpal height (mm) |
69.81 ± 4.69 |
65.69 ± 4.09 |
0.001* |
capitates length (mm) |
24.95 ± 1.72 |
22.27 ± 1.39 |
0.001* |
carpal height ratio |
0.48 ± 0.47 |
0.46 ± 0.37 |
0.001* |
carpal height ratio revised |
1.35 ± 0.72 |
1.36 ± 0.66 |
0.211 |
| *p considered significant at <0.05 |
None of the parameters measured and the indices calculated showed significant variations in the different age-groups (p>0.05) (Table 4). Table 5 shows the mean carpal parameters and indices documented in previous radiographic studies from different populations.
| Table 4: Carpal measurements in the different age-groups |
Variable |
Age-groups (Years) |
P value |
|
21-30 |
31-40 |
41-50 |
51-60 |
61-70 |
71-80 |
81-90 |
|
Carpal height (mm) |
32.42 ± 2.37 |
31.57 ± 2.64 |
32.34 ± 2.08 |
31.45 ± 2.43 |
31.77 ± 2.88 |
30.56 ± 3.46 |
34.83 ± 0.67 |
0.144 |
Middle metacarpal height (mm) |
68.71 ± 3.63 |
67.12 ± 4.89 |
68.10 ± 3.40 |
68.39 ± 4.70 |
66.73 ± 5.47 |
63.68 ± 5.45 |
66.87 ± 7.58 |
0.080 |
Capitate length (mm) |
23.53 ± 1.44 |
23.23 ± 2.16 |
23.61 ± 1.78 |
23.60 ± 1.95 |
23.60 ± 2.54 |
22.28 ± 2.33 |
23.90 ± 1.06 |
0.555 |
Carpal height ratio |
0.47 ± 0.04 |
0.47 ± 0.05 |
0.47 ± 0.03 |
0.46 ± 0.03 |
0.47 ± 0.02 |
0.47 ± 0.06 |
0.50 ± 0.06 |
0.706 |
Carpal height ratio revised |
1.38 ± 0.08 |
1.36 ± 0.07 |
1.37 ± 0.07 |
1.33 ± 0.05 |
1.34 ± 0.04 |
1.35 ± 0.09 |
1.41 ± 0.05 |
0.342 |
| Table 5: Radiographic carpal measurements and indices in different populations |
Author |
Country |
N |
Carpal height (mm) |
3rd metacarpal height (mm) |
Capitate length (mm) |
Carpal height ratio |
Revised carpal height ratio |
Youm et al., 1978 [10] |
Iowa |
62 |
|
|
|
0.54±0.03 |
|
Nattrass et al., 1994 [11] |
Canada |
100 |
|
|
|
|
1.57±0.05 |
Foteva and Poposka, 2010 [12] |
Macedonia |
100 |
32.78±3.0 |
|
|
0.53±0.02 |
1.56±0.02 |
Wang et al., 2010 [13] |
Taiwan |
261 |
|
|
|
0.51±0.03 |
|
Jafari et al., 2012 [5] |
Iran |
150 |
32.2±2.8 |
61.4±5.6 |
21.8±2.3 |
0.52 |
1.5±0.09 |
Vaezi et al., 2017 [6] |
Mashhad |
100 |
37.1±3.8 |
70.1±5.55 |
23.8±2.39 |
|
|
Tang et al., 2018 [7] |
China |
71 |
31.8±3.0 |
|
|
|
|
Jehan et al., 2018 [3] |
India |
120 |
|
|
|
0.52±0.05 |
1.50±0.06 |
Yalcin and Polat, 2022 [4] |
Turkey |
320 |
32.69±3.37 |
65.09±34.7 |
21.95±2.28 |
0.52±0.06 |
1.49±0.1 |
Current study |
Nigeria |
135 |
31.77±2.63 |
67.34±4.78 |
23.34±2.02 |
0.47±0.04 |
1.36±0.07 |
Discussion
The average carpal height in this study was 31.77mm±2.63 and this was lower than the findings reported in China, Mashhad, Macedonia and Iran. (5-7, 12) According to Tang et al. (7), the evaluation of the PA wrist radiographs of Chinese patients did not show any significant side differences in the carpal height. (7) The present study did not evaluate for side differences since the radiographs used were of unpaired wrists. The average third metacarpal height and capitate length herein were lower than the findings of Tohid et al. (6) and higher than the reports of Jafari et al. (5)
The Carpal Height Ratio (CHR) was first described by Youm et al. (10) who reported a normal value of 0.54 ± 0.04. Several studies documented in literature have reported varying CHR. A radiographic study in Taiwan documented a mean CHR of 0.51. (13) An average CHR of 0.52 was reported in Turkey, India and Iran. (3- 5) Another study by Foteva and
Poposka (12) reported a CHR of 0.53 from the parameters measured on wrist radiographs in Macedonia. (12) The CHR in the current study (0.47) was lower than all the above mentioned studies (Table 5). Nattrass et al. (11) introduced the CHRr and reported a normal value of 1.57±0.05. Previously documented studies reported the mean CHRr of 1.56 in Macedonia, 1.49 in Turkey and 1.5 in India and Iran. (3-5,12) The present study reports a lower mean CHRr of 1.36 compared to these earlier reports.
Consistent with the reports of Tohid et al. (6) and Jafari et al. (5), the carpal height, third metacarpal height and capitate length were significantly larger in males than in females. This could be ascribed to the differences in the sex hormones whereby, testosterone in males significantly contributes to the growth of bones leading to larger bones in males than in females. On the contrary, Foteva and Poposka (12) did not observe any significant gender difference in the carpal height. The metric parameters in the present study showed no significant differences in the various age-groups and this was congruent with the findings of Tohid et al. (6) and Tang et al. (7) Jafari et al. (5) categorized 150 normal wrist radiographs of Iranian patients into two age groups of 20-40 years and 41-60 years. They observed significantly smaller 3rd metacarpal length, capitate length and carpal height in the older age-group. These variations were attributed to the differences in the gender distribution of radiographs in the two age-groups whereby, majority of the radiographs in the 41-60 years’ age-group belonged to female patients.
Corresponding with the reports of Wang et al. (13), the present study reports a significant gender difference in the carpal height ratio. However, this contrasted with the reports of Foteva and Poposka (12), Jafari et al (5), Jehan et al (3) and Yalçin and Polat (4) who did not observe any significant gender difference in the CHR. Consistent with previously documented studies, the CHRr did not show any significant association with gender implying that the ratio is the same in males and females. (3-5, 12) The CHR and CHRr in the current study did not show any significant differences in the various age-groups. Similarly, this was documented by several previous studies. (3- 6, 13)
The population differences in the carpal indices and ratios could be attributed to individual, racial and ethnic anatomic dissimilarities. (3, 6) Additionally, handedness may contribute to the differences in the carpal indices since repetitive wrist movements by the dominant hand may influence the size of the carpal bones. The discrepancies could also be ascribed to differences in the sample size and sample composition based on age-group and gender distribution in the different studies. (4,6) Moreover, the variations could be due to the different inclusion criteria employed in selecting the wrist radiographs whereby, Shariatzade et al. (8) used radiographs of patients with different stages of Kienbock’s disease. Similar to Jehan et al (3) and Yalcin and Polat (4), the present study excluded radiographs with evidence of pathology. Tohid et al. (6) studied the wrist indices in healthy participants recruited from the patients’ relatives. According to Jehan et al (3), the different degrees of magnification on the radiographs could be responsible for the variations in the carpal height. Additionally, Jafari et al (5) documented that the proper positioning of the hand, forearm, elbow and shoulder during radiograph acquisition affects the accuracy of the measurements. These variations affect the accuracy of diagnosis of wrist pathology. Therefore, population specific references should be considered. (6)
The findings of this study will help orthopedic surgeons in the studied population to diagnose carpal collapse and advise on the appropriate treatment approach. According to Tang et al. (7), the presence of carpal collapse in Kienbock’s disease may require proximal row carpectomy. On the other hand, the absence of carpal collapse may suggest the need for lunate protection and reconstruction. According to Jafari et al. (5), CHR is a sensitive index of the carpal anatomy and is usually decreased in advanced stages of Kienbock’s disease, osteoarthritis and scaphoid non-union. Shariatzade et al. (8) used radiographs of patients with Kienbock’s disease and diagnosed carpal collapse when CHR was less than 0.51 and CHRr was less than 1.52.
Conclusion
The CHR and CHRr in this study were lower than reports from other population groups. The findings therefore provide reference database to aid in accurate diagnosis and effective management of carpal collapse in the studied population.
Limitations
The sample size used in this study was small due to the retrospective nature of the study and the use of purposive sampling technique involving only apparently normal radiographs from a single study center.
Recommendation
A larger multi-centered study can be conducted to determine these carpal indices in Delta State Nigeria. Moreover, a further study can be conducted to compare these variables in normal and affected wrists.
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