LOCALIZATION OF THE TIBIAL ENTRY POINT.

OBJECTIVE: To assess the intramedullary nail entry point in the proximal region of the tibia, through a questionnaire.
METHODS: 230 participants undergoing treatment for tibial fractures were interviewed. The questionnaire was created with three sections that could be answered in a "Yes" or "No" format and a fourth section that had two figures representing anteroposterior (AP) and lateral view x-rays that could be answered in an "A, "B" or "C" format.
RESULTS: The most frequent reason was "ease of access" (67.8%), followed by "better nail insertion access" (60.9%) and, in third place, "to prevent knee pain" (27.4%). The reasons for choosing the access so as to "prevent knee pain" and "avoid tendinitis" had a significant relationship with points "A" and "C" of the schematic AP x-ray figure, especially "C" (medial tibial crest). There were no significant differences between the types of access to the patellar ligament in the schematic AP and lateral x-ray figures between age groups.
CONCLUSION: The greater the age was, the larger the proportion choosing the question "to avoid valgus deformity" was. The reasons from a medical (practical) perspective related to the type of access in the transpatellar ligament, while the reasons from a patient (functional) perspective related to medial parapatellar access. Transpatellar access was chosen by most of the participants (66.5%).

INTRODUCTION

Fractures of the tibial diaphysis remain the commonest injury treated by orthopedic surgeons. Intramedullary nails have become the treatment of choice both for unstable closed fractures and for low-energy exposed fractures1, 2. A variety of entry points in the proximal region of the tibia have been described, but the ideal location remains a topic of discussion1, 3, 4, 5, 6. Several surgical accesses can be used to obtain the entry point, including medial and lateral parapatellar access and transpatellar incision1, 4, 7. According to the literature, authors have reported complications such as pain in the anterior region of the knee, ligament instability, necrosis of the retropatellar fat, cartilage and meniscus lesions, reflex sympathetic dystrophy, gait abnormality and tenosynovitis as possible cause of the surgical procedure7, 8, 9, 10, 11, 12, 13, 14. However, sometimes the pain is not relieved by removing the nail, and the transpatellar incision has been partially implicated as the cause of these complications7, 8, 9, 10, 12. The aim of the present study was to investigate the intramedullary nail entry point in the proximal region of the tibia, by means of a questionnaire answered at the Brazilian Congress of Orthopedics and Traumatology.

METHODS

During the 40th Brazilian Congress of Orthopedics and Traumatology, which took place in Rio Grande do Sul in 2008, 230 participants who treat tibial fractures were interviewed to obtain information. The questionnaire was formulated with three sections that could be answered in a “yes” or “no” format and a fourth section containing two figures representing anteroposterior (AP) and lateral view radiographs that could be answered in an “A”, “B” or “C” format. The participants were divided into three categories according to age group (25-35, 36-45 and > 45 years), in order to find out whether the surgeon's experience would influence the results.

The orthopedists were asked whether they treated fractures of the tibial diaphysis using an intramedullary nail. If so, they were asked whether they used one or more accesses. In relation to the patellar ligament, they were asked whether they used a medial, lateral or transpatellar access. They were also asked what the reason was for their selection of access to the patellar ligament (see annexed questionnaire)

Participation was voluntary and the responses were confidential. The results were calculated and subjected to statistical analysis.

General profile of the sample

The aim was to describe the profile of the 230 participants in accordance with the questionnaire for evaluating the entry point for the intramedullary nail in the tibia. Table 1 furnishes the frequency (n) and percentage (%) of the responses to the questionnaire, for the whole sample.

Table 1

Description of the questionnaire for 230 respondent participants

Variable	Category	n	%
Age groupa	25 to 35 years	95	42.0
36 to 45 years	71	31.5
> 45 years	60	26.5
Access for nail emplacement	Single access	201	87.4
Several types	29	12.6
Patellar ligament	Medial	64	27.8
Transpatellar	153	66.5
Lateral	13	5.7
Reason for selecting the ligament access	1. To prevent knee pain	63	27.4
2. To preserve the patellofemoral biomechanics	49	21.3
3. To improve the access for nail insertion	140	60.9
4. Ease of access	156	67.8
5. Localization of the fracture	21	9.1
6. To avoid neuroma formation	8	3.5
7. To avoid valgus deformity	22	9.6
8. To avoid varus deformity	14	6.1
9. To avoid tendinitis	48	20.9
Radiographic reference – 1b	A	32	14.4
B	149	66.8
C	42	18.8
Radiographic reference - 2b	A	61	27.4
B	120	53.8
C	42	18.8
Comments	Yes	13	5.7
No	217	94.3

No information in relation to four patients.

No information in relation to seven patients.

STATISTICAL ANALYSIS

The statistical tests applied were the chi-square (χ2) or Fisher exact test, to compare proportions between data of categorical nature. The results were presented in tables and expressed by means of frequencies (n) and percentages (%). The criterion used for determining the significance was the level of 5%. The statistical analysis was processed using the statistical software of the SAS® System, version 6.04.

RESULTS

Among the reasons for choosing the surgical access, it was seen that the most frequent reason was “ease of access” (67.8%), followed by “better access for nail insertion” (60.9%) and, in third place, “to prevent knee pain” (27.4%). Figure 1 illustrates the distribution of the reasons for selecting the access in the patellar ligament.

Figure 1

Percentages of the reasons for choosing the access in the patellar ligament

From the responses of the 230 participants, it was investigated whether there were any significant differences in the proportions of reasons for access choice between the age groups, and what types of access were used in relation to the patellar ligament and the reference locations on the schematic radiographs.

Tables 2, 3, 4 and 5 show the frequencies (n) and percentages (%) of the reasons for choosing the access route according to the age group (25-35, 36-45 and > 45 years), types of access in relation to the patellar ligament (medial, transpatellar and lateral) and radiographic reference locations, in accordance with Figures A, B and C of the annexed questionnaire, respectively, along with the corresponding descriptive level in the statistical test (p). The statistical analysis was performed using the χ2 or Fisher exact test.

Table 2

Statistical analysis on the reasons for choosing the access, according to age group

Age group	25 to 35 years		36 to 45 years		> 45 years		p
Reason for selecting the access	n	%	n	%	n	%
1. To prevent knee pain	28	29.5	15	21.1	20	33.3	0.27
2. To preserve the patellofemoral biomechanics	18	19.0	12	16.9	18	30.0	0.14
3. To improve the access for nail insertion	60	63.2	46	64.8	32	53.3	0.35
4. Ease of access	66	69.5	51	71.8	37	61.7	0.43
5. Localization of the fracture	8	8.4	5	7.0	8	13.3	0.43
6. To avoid neuroma formation	2	2.1	1	1.4	4	6.7	fc
7. To avoid valgus deformity	3	3.2	8	11.3	11	18.3	0.007
8. To avoid varus deformity	4	4.2	4	5.6	6	10.0	fc
9. To avoid tendinitis	19	20.0	13	18.3	16	26.7	0.47

fc: Few cases.

Table 3

Statistical analysis on the reasons for selecting the access to the patellar ligament

Patellar ligament	Medial		Transpatellar		Lateral		p*
Reason for selecting the access	n	%	n	%	n	%
1. To prevent knee pain	38	59.4	16	10.5	9	69.2	<0.0001
2. To preserve the patellofemoral biomechanics	27	42.2	14	9.2	8	61.5	<0.0001
3. To improve the access for nail insertion	23	35.9	112	73.2	5	38.5	<0.0001
4. Ease of access	29	45.3	122	79.7	5	38.5	<0.0001
5. Localization of the fracture	4	6.3	16	10.5	1	7.7	0.32
6. To avoid neuroma formation	2	3.1	5	3.3	1	7.7	fc
7. To avoid valgus deformity	5	7.8	16	10.5	1	7.7	0.54
8. To avoid varus deformity	3	4.7	10	6.5	1	7.7	fc
9. To avoid tendinitis	33	51.6	5	3.3	10	76.9	< 0.0001

fc: Few cases.

a Comparison between medial and transpatellar.

Table 4

Statistical analysis on the reasons for selecting the access, according to the radiographic reference location - schematic figure of the AP radiograph

Radiographic reference 1	Point A		Point B		Point C		p
Reason for selecting the access	n	%	N	%	n	%
1. To prevent knee pain	10	31.3	31	20.8	20	47.6	0.002
2. To preserve the patellofemoral biomechanics	9	28.1	27	18.1	12	28.6	0.21
3. To improve the access for nail insertion	16	50.0	96	64.4	23	54.8	0.22
4. Ease of access	19	59.4	108	72.5	25	59.5	0.14
5. Localization of the fracture	2	6.3	15	10.1	4	9.5	0.88
6. To avoid neuroma formation	2	6.3	4	2.7	2	4.8	fc
7. To avoid valgus deformity	2	6.3	14	9.4	6	14.3	0.55
8. To avoid varus deformity	2	6.3	10	6.7	2	4.8	fc
9. To avoid tendinitis	11	34.4	19	12.8	16	38.1	< 0.0001

fc: Few cases.

Table 5

Statistical analysis on the reasons for selecting the access, according to the radiographic reference location - schematic figure of the lateral radiograph

Radiographic reference 2	Point A		Point B		Point C		p
Reason for selecting the access	n	%	n	%	n	%
1. To prevent knee pain	15	24.6	33	27.5	13	31.0	0.77
2. To preserve the patellofemoral biomechanics	11	18.0	26	21.7	11	26.2	0.61
3. To improve the access for nail insertion	34	55.7	73	60.8	28	66.7	0.53
4. Ease of access	40	65.6	84	70.0	28	66.7	0.81
5. Localization of the fracture	5	8.2	12	10.0	4	9.5	0.92
6. To avoid neuroma formation	1	1.6	4	3.3	3	7.1	fc
7. To avoid valgus deformity	2	3.3	9	7.5	11	26.2	<0.0001
8. To avoid varus deformity	1	1.6	5	4.2	8	19.1	fc
9. To avoid tendinitis	14	23.0	23	19.2	9	21.4	0.82

fc: Few cases.

It was not possible to analyze the reasons “to avoid neuroma formation” and “to avoid varus deformities” because of the low frequencies observed.

It was seen that there was a statistical difference between the age groups only in relation to the reason “to avoid valgus deformity” (p = 0.007), i.e. the older the age group was, the higher the proportion of the participants choosing this reason was. There were no significant differences in the proportions of the other reasons, at the 5% level.

For analysis purposes, access to the lateral ligament was not taken into consideration because of the low frequency observed (n = 13). It was seen that reasons from a medical (practical) perspective, such as “better access for nail insertion” and “ease of access”, were significantly related to transpatellar access.

On the other hand, reasons from a patient (functional) perspective, such as “to prevent knee pain”, “to preserve the biomechanics” and “to avoid tendinitis” were significantly correlated with the medial parapatellar access. It was found that there was a significant relationship between the reasons for access choice, such as “to prevent knee pain” (p = 0.002) and “to avoid tendinitis” (p < 0.0001), and the points A and C on the schematic figure of the AP radiograph, particularly the point C (medial tibial crest). No significant differences in the proportions of the other reasons were found between the locations of the schematic figure of the AP radiograph, at the 5% level. Although without significance, reasons for the access from a medical perspective predominated, such as “better access for insertion” and “ease of access”, at the radiographic reference location point B.

It was seen that there was a significant relationship only between the reason “to avoid valgus deformity” (p < 0.0001) and the radiographic reference location point C on the schematic figure of the lateral radiograph. There were no significant differences in the proportions of the other reasons between the radiographic reference locations, at the 5% level. Table 6 furnishes the frequencies (n) and percentages (%) of the type of access, in relation to the patellar ligament (medial, transpatellar and lateral) and the radiographic reference location (Figures A, B and C) of the questionnaire, according to the age group (25-35, 36-45 and > 45 years), and the corresponding descriptive level of the statistical test (p). The statistical analysis was performed using the χ2 test. It was observed that there was a significant difference between the reference location on the schematic figure of the AP radiograph (p < 0.0001) and the type of access in relation to the patellar ligament, i.e. the lateral access predominated at point A, the transpatellar access at point B and the medial at points C and B, in this order. It was noted that there were no significant differences in the types of access in relation to the patellar ligament (p = 0.78), in the schematic figures of the AP radiograph (p = 0.33) and lateral radiograph (p = 0.65), between the age groups, at the 5% level.

Table 6

Statistical analysis on the type of access in relation to the patellar ligament and radiographic reference, according to age group

Variable	Category	25 to 35 years		36 to 45 years		> 45 years		p
n	%	n	%	n	%
Patellar ligament	Medial	26	27.4	20	28.2	17	28.3	0.78
Transpatellar	62	65.3	49	69.0	39	65.0
Lateral	7	7.4	2	2.8	4	6.7
Radiographic reference Figure 1	Point A	15	15.8	6	9.0	10	17.5	0.33
Point B	65	68.4	49	73.1	33	57.9
Point C	15	15.8	12	17.9	14	24.6
Radiographic reference Figure 2	Point A	26	27.4	19	28.4	15	26.3	0.65
Point B	55	57.9	35	52.2	28	49.1
Point C	14	14.7	13	19.4	14	24.6

DISCUSSION

Intramedullary nails are the treatment of choice for unstable closed fractures of the tibial diaphysis and for exposed low-energy fractures2, 15. Success in emplacing the tibial nail depends on the location and on the insertion angle. The ideal entry point for tibial nails has been the subject of much discussion. Freeman and Johnson demonstrated that the angle between the longitudinal axis of the nail and the proximal fragment is more important that the insertion point, for maintaining the bone alignment after nail treatment for a proximal fracture of the tibia. However, an inappropriate entry point may lead to deviation of the nail against the proximal cortex. Alms recommended using a lateral entry point above the anterosuperior extrasynovial surface. Chapman determined an entry point above the anterior tuberosity of the tibia, via a transpatellar route. Tornetta et al described an anatomical safety zone for emplacement of a nail, in an area of approximately 22.9 mm. That study indicated that lesions of the lateral or medial meniscus might be responsible for the pain in the knee. McConnell et al demonstrated that the ideal entry point would be medial to the lateral tibial spine in AP view and immediately adjacent to the anterior margin of the joint surface in lateral view.

In the present study, the surgeon's experience was analyzed according to the reasons for selecting the access, in relation to three age groups (25-35, 36-45 and > 45 years). In all of the age groups, achieving “the best access for nail insertion” and “ease of access” were major concerns. However, it was observed that there was greater concern in relation to valgus deformity, i.e. the older the age group was, the higher the proportion choosing this reason was. Lang et al observed that defective consolidation with valgus in tibial fractures was caused by a medial entry point and a nail insertion angle directed laterally in the proximal fragment.

For the point of entry in the tibia to be accessed, the incision can be lateral or medial parapatellar or transpatellar. Several authors have reported high incidence of knee pain with the transpatellar access, after insertion of the intramedullary nail, and have suggested that a paratendinous access would help to diminish this symptom 7, 8, 10, 11, 13, 19, 20. Our results demonstrate that, independent of the age group, most participants used the transpatellar access and that only 27.4% expressed concern regarding knee pain. However, among the participants who chose the medial parapatellar access, 59.4% expressed concern about preventing knee pain. Within the general context, it was seen that the reasons for choosing the access were divided into two perspectives. In the first of these, which we have called medical (practical), reasons like “better access for nail insertion” (60.9%) and “ease of access” (67.8%) were selected and were correlated with the transpatellar type of access. In the second, called the patient (functional) perspective, concern regarding the final result was expressed through choosing reasons like “to prevent knee pain” (27.4%), “to preserve the patellofemoral biomechanics” (21.3%) and “to avoid tendinitis” (20.9%). These reasons were correlated with use of the medial parapatellar access. Althausen et al reserved transpatellar access for tibias with an ideal entry point located in the central position and behind the patellar tendon, in proximal fractures of the tibia, thus leaving parapatellar access for other fracture patterns. They also recommended using nails with low curvature (Herzog curve), in order to achieve the best alignment possible.

McConnell et al demonstrated that the ideal entry point was medial to the lateral tibial spine in AP view and immediately adjacent to the anterior margin of the joint surface in lateral view. Samuelson et al found good results using a medial parapatellar access and also using the transpatellar access when they avoided the insertion site lateral to the tibial tubercle. Althausen et al concluded that there were anatomical variations between the patellar tendon and the lateral tibial spine. This variation would imply that a routine surgical access might not give the ideal direction for the entry point. Preoperative assessment using fluoroscopy might direct the surgeon towards the best access for reaching the entry point. Our results demonstrate that most of the participants chose point B from the schematic figure of both the AP and the lateral radiograph (66.8% and 53.8%, respectively). Only 13 participants (5.7%) made any comments regarding the nail insertion site. It was seen that there was a relationship between the reasons from the patient (functional) perspective, such as “to prevent knee pain” and “to avoid tendinitis”, and the points A and C, while the reasons from the medical (functional) perspective, such as “better access for insertion” and “ease of access”, predominantly correlated with point B of the schematic figure of the AP radiograph. With regard to the reasons for selecting the access according to the schematic figure of the lateral radiograph, there was only a relationship between the reason “to avoid valgus deformity” and point C.

CONCLUSION

It was found that the older the age group was, the higher the proportion choosing the reason “to avoid valgus deformity” was. The reasons from the medical (practical) perspective, such as “better access for nail insertion” and “ease of access” were correlated with the transpatellar access, while the reasons from the patient (functional) perspective, such as “to present knee pain”, “to preserve the biomechanics” and “to avoid tendinitis” were correlated with the medial parapatellar access. The transpatellar access was chosen by the majority of the participants (66.5%).

Questionnaire for evaluating the entry point for intramedullary nails in the tibia