Application of the Chinese Aircraft-shaped Sleeve system in the treatment of tibial shaft fractures using a suprapatellar approach for tibial intramedullary nailing: a randomised controlled trial
DOI: 10.1186/s13018-018-0995-7
© The Author(s). 2018
Received: 4 October 2018
Accepted: 2 November 2018
Published: 14 November 2018
Abstract
Background
The use of the suprapatellar approach for intramedullary nailing has recently become popular for the treatment of tibial fractures. This study aimed to investigate the effectiveness of using the Chinese Aircraft-shaped Sleeve (CASS) system on the clinical outcomes of tibial intermedullary nailing using a suprapatellar approach for the treatment of tibial fractures in a cohort of adult Chinese patients.
Methods
Magnetic resonance images (MRI) of the knee joints of 212 healthy adults with normal lower limb function from May 2011 to May 2015 were obtained from a level I Chinese regional trauma centre. Sixty inpatients at the same trauma centre who underwent treatment for tibial shaft fractures from June 2015 to June 2018 were enrolled. Tibial intramedullary nailing fixation of tibial shaft fractures via the suprapatellar approach was performed with either a CASS system or a conventional sleeve. The measurements of patellofemoral joint anatomy, the surgical time, the assessments of the patellofemoral joint cartilage conditions, and information of residual debris based on arthroscopic analysis were subsequently collected.
Results
The mean patellar angle (PA), sulcus angle (SA), sulcus width (SW) and sulcus depth (SD) were 135.40 ± 6.20°, 142.37 ± 5.33°, 33.37 ± 2.73 mm, and 4.29 ± 0.63 mm, respectively. The surgical time until entry reaming commencement and the irrigation time were significantly lower in the CASS group (P < 0.001). The difference in cartilage damage rate between groups was statistically significant (P = 0.031); the difference in residual debris conditions was not statistically significant (P = 0.1967).
Conclusion
The use of the CASS system could improve clinical outcomes of intramedullary nailing via suprapatellar approach for patients with a small patellofemoral joint space.
Keywords
Suprapatellar approach Tibial fracture Intramedullary nailing Sleeve Magnetic resonance Patellofemoral jointAbbreviations
- CASS:
-
Chinese Aircraft-shaped Sleeve
- IMN:
-
Intramedullary nailing
- MRI:
-
Magnetic resonance image
- PA:
-
Patellar angle
- PEEK:
-
Polyetheretherketone
- SA:
-
Sulcus angle
- SD:
-
Sulcus depth
- SW:
-
Sulcus width
- TU:
-
Thermoplastic polyurethane
Background
Tibial fractures are one of the most common long bone fractures in the human body. Intramedullary nailing (IMN) has become the preferred treatment choice for tibial fractures, particularly those of the shaft, as it is minimally invasive and ensures high fixation strength, which allows patients to return to routine activities immediately after surgery [1]. The traditional surgical approach for IMN begins with an incision below the patella (in the middle or along the patellar ligament), with an insertion of the nail with the knee joint flexed to at least 90°. In 1996, Tornetta and Collins [2] first reported a suprapatellar approach, performed with the knee in a semi-extended position (in about 15° of flexion), using a mid-line incision, from the superior patellar pole to the tibial tubercle, followed by the creation of a slit through two-thirds of the medial patellar retinaculum to sublux the patella.
Methods
Anatomical parameters of the Chinese Aircraft-shaped Sleeve (CASS) system
The study was approved by our institutional review board and ethics committee and all participants provided informed consent.
Magnetic resonance images (MRI) of the knee joints of 212 healthy adults with normal lower limb function were obtained from May 2011 to May 2015 from a level I Chinese regional trauma centre. The exclusion criteria were as follows: previous history of knee surgery, trauma, space-occupying lesions in the knee joint and surrounding areas, patellar softening, sulcus dysplasia, synovial hyperplasia, and severe fluid accumulation in the joints. Of the 212 patients, 101 were men and 111 were women, and the age range was 18–73 years (mean 41 years). In total, there were 106 left knees and 106 right knees. The MRIs were obtained using a 1.5-T system (Philips 1.5-T Achieva, Philips, Netherlands) with patients in the supine position with full knee extension. Axial T2-weighted (TR/TE: shortest/100, matrix 256 × 192, FOV 160 × 160, slice thickness 3 mm) sequences were obtained. MRIs were analysed on a workstation (Centricity RIS CE V3.0, General electric medical system (China) Co., Ltd., USA) by one radiologist, and measurements were made using electronic callipers.
Application of the CASS system
Sixty inpatients who underwent treatment for a tibial shaft fracture at our centre, between June 2015 and June 2018, were enrolled. The selection criteria were as follows: (1) tibial shaft fractures (OTA type 42), (2) achievement of mature bone, and (3) the use of the Expert Tibial Nail system (ETN; DePuy Synthes, USA), with a suprapatellar approach. The exclusion criteria were as follows: (1) knee injury or stiffness, (2) patella baja, (3) patellar ligament calcification, (4) existing vascular nerve injury, (5) soft tissue injury around the incision area, and (6) metabolic or pathological bone diseases. After patients were enrolled in the study, each received a sealed envelope containing a randomised number, generated using SAS 9.2 (SAS Institute, Inc., Cary, NC, USA) based on the order of admission, for allocation to either the CASS group or the conventional sleeve group, in a 1:1 ratio.
The general characteristics of the patient group were as follows: 33 men and 27 women, with an age range of 22 to 69 years. There were no significant differences in baseline conditions between the CASS and conventional sleeve group. All procedures were performed by one senior surgeon. Due to the specific nature of the intervention methods, double-blinding could not be achieved between the surgeon and patients. Data processing, statistical analysis, and evaluations were performed by independent professionals who had no knowledge of group assignment.
Sample size
Based on preliminary tests and a previous study [3], we initially defined the primary outcome as the rate of cartilage damage, with an estimated rate of 0.03 in the treatment group (CASS group) and 0.28 in the control group (conventional sleeve group). The ratio between the sample sizes of the two groups was 1:1. Using an α value of 0.05 and β value of 0.2 (power of 0.80), the minimum requirement, based on the SAS sample size calculator procedure [4], was 30 patients per group.
Surgical treatment
The conventional sleeve group underwent surgery using traditional suprapatellar procedures for the ETN system (DePuy Synthes, Raynham, MA, USA). The incision and joint cavity were irrigated repeatedly with a solution volume of 4000 ml.
Clinical outcomes
The following outcomes were obtained for analysis: surgical time, calculated up to the point of remaining; arthroscopic assessment of the condition of the patellofemoral joint cartilage at two time points (once after deep separation, before sleeve insertion, and once after insertion of the end cap), using a Smith & Nephew arthroscope system (Smith & Nephew, Andover, MA, USA); the Outerbridge scale [5] which provides a grading of cartilage damage (grade 0, normal; grade I, cartilage with swelling and softening; grade II, fragmentation and fissuring in an area ≤ 0.5 in. in diameter; grade III, fragmentation and fissuring in an area > 0.5 in. diameter; and grade IV, erosion of the cartilage down to the bone); and the irrigation time. The number of cases with (positive) or without (negative) cartilage damage and residual debris was recorded for both groups. Arthroscopic evaluations were performed by a sports medicine expert, who did not have knowledge of group allocation.
Statistics
Statistical analysis was performed using SAS 9.2 (SAS Institute, Inc., Cary, NC, USA). The data collected for PA, SA, SW, and SD were divided into two groups by sex. A t test was used to compare the sample means, adopting a completely randomised design. The Shapiro-Wilk test was used to test data normality, and the F test was used to evaluate the homogeneity of variance. The chi-square test, with correction for continuity in a 2 × 2 table, was used to compare the cartilage damage rate and the residual rate of debris between the groups. P < 0.05 indicated statistical significance.
Results
Measurements of patellofemoral joint anatomy in 212 normal adult Chinese people
Measured parameter | Men (n = 101) | Women (n = 111) | Total | P value* |
---|---|---|---|---|
Patella angle (°) | 137.30 ± 6.02 | 133.68 ± 5.87 | 135.40 ± 6.20 | < 0.001 |
Sulcus angle (°) | 142.62 ± 5.32 | 142.14 ± 5.36 | 142.37 ± 5.33 | 0.5128 |
Sulcus width (mm) | 35.17 ± 2.23 | 31.72 ± 2.01 | 33.37 ± 2.73 | < 0.001 |
Sulcus depth (mm) | 4.54 ± 0.58 | 4.06 ± 0.58 | 4.29 ± 0.63 | < 0.001 |
Comparison of cartilage damage rate between 30 patients in the Chinese Aircraft-shaped Sleeve group and 30 patients in the conventional sleeve group
Group | Positive | Negative | Total | Residual rate (%) | P value* |
---|---|---|---|---|---|
Chinese Aircraft-shaped Sleeve group | 1 | 29 | 30 | 3.33 | 0.0301 |
Conventional sleeve group | 8 | 22 | 30 | 26.67 | |
Total | 9 | 51 | 60 | 15.00 |
Comparison of postoperative residual rate of debris between 30 patients in the Chinese Aircraft-shaped Sleeve group and 30 patients in the conventional sleeve group
Group | Positive | Negative | Total | Residual rate (%) | P value* |
---|---|---|---|---|---|
Chinese Aircraft-shaped Sleeve group | 1 | 29 | 30 | 3.33 | 0.1967 |
Conventional sleeve group | 5 | 25 | 30 | 16.67 | |
Total | 6 | 54 | 60 | 10.00 |
Discussion
The suprapatellar approach is initiated through the patellofemoral joint gap. As such, the relatively smaller body size of Chinese individuals, compared to Westerners, reduces the joint space available for manoeuvring and insertion of the intramedullary nail. It is to address this specific issue of size difference between two ethnic populations that we developed the CASS based on reliable anatomical parameters of the patellofemoral joint measured in a sample group of 212 individuals using MRI. MRI was selected as it effectively displays cartilage and periarticular soft tissues [6]. MRI also provides images in multiple views, which facilitates observation of the patellofemoral joint from various angles, accurately displaying the area of contact between the patella and the femoral sulcus [7]. It has been suggested that the sulcus angle is consistently smaller when measured from subchondral bone than from cartilage (5–7°). Moreover, MRI is the most suitable tool for longitudinal studies of the femoral sulcus [8]. Therefore, the MRIs of the knee joints of 212 healthy Chinese people were evaluated; measurements among women were significantly smaller than those among men (P < 0.05).
Although soft tissue has a certain degree of elasticity and the patella is lifted after incising the quadriceps, it is difficult to insert a protective sleeve into the narrow patellofemoral joints of Chinese surgical patients, and this is especially true of Chinese women, which increases operative time. Moreover, we observed greater pressure being exerted on the protective sleeve inside the patellofemoral joint (Fig. 8). Careless or forceful insertion of an intramedullary nail through a deformed sleeve increases the risk for iatrogenic injury. In our study, two patients in the conventional sleeve group experienced articular cartilage damage because of damaged sleeves (Fig. 9). Yasuda et al. [9] proposed an improved parapatellar approach for the narrow patellofemoral joint gap. This approach includes a 5–6-cm skin incision made on the lateral side of the patella and slitting of the lateral patellar retinaculum until the joint capsule can be opened, with a 2–0 absorbable monofilament suture used to achieve and maintain patellar eversion. Following this alternate procedure, conventional tibial reaming and IMN were performed. However, this approach to increasing the surgical workspace requires cutting the retinaculum surrounding the patella. In a cadaver study, Sandmeier et al. [10] compared the patellar tracking status of intact, incised, and reconstructed medial patellar retinacula. With the application of a lateral stress, patellar tracking changed significantly after medial retinaculum incision. After reconstruction, patellar tracking improved, but could not be restored to a completely normal state. Therefore, we believe that the suprapatellar approach to retinaculum incision for patellar subluxation requires further study.
Another difficulty that has previously been encountered during positioning is related to the use of a circular hollow sleeve to protect the patellofemoral joint in the traditional suprapatellar approach. Tajima et al. [3] designed a heart-shaped outer sleeve for the suprapatellar approach. The ventral side of the sleeve was affixed to the posterior articular surface of the patella at 130°. The dorsal side was affixed to the femoral sulcus at 140°. In our measurement of anatomical parameters, we determined that these angles are inappropriate for Chinese individuals, with a PA of 135.40 ± 6.20° and SA of 142.37 ± 5.33° when the medial and lateral cartilage surfaces of the patella and sulcus, respectively, meet in the middle. Based on these measurements, we designed an anatomically correct protective outer sleeve (aircraft wings), with a ventral face angle of 135° and the dorsal face angle of 142°.
The suprapatellar approach is performed through the joint cavity, and debris are generated when open reaming is performed. If debris remain in the joint cavity after the intraoperative procedures, there is a risk of heterotopic ossification or joint mice. Sanders et al. [13] reported that debris does not form new bones in synovial fluid; hence, heterotopic ossification is not a serious problem, but thorough postoperative irrigation is still necessary. In the conventional suprapatellar approach, the flow rate is limited, the direction of flow is not controllable, and blind angles are not easily irrigated. Consequently, the irrigation time tends to be long and the process may not be sufficiently thorough to avoid postoperative issues. To avoid this, it is mandatory to use a large amount of saline to perform pressurised irrigation in all directions. Currently, there are no relevant studies to indicate the amount of solution that is needed. We referred to a study by Niki et al. [16] that investigated the amount of saline needed for effective irrigation in total knee arthroplasty. Their results showed that 4000 ml of pulsed irrigation was the most efficient method of removing bone and bone cement debris. Therefore, in this study, we also used 4000 ml of rinsing solution. Our conventional sleeve group had a total irrigation time of 16.7 ± 0.9 min, which was considered a long time. It was clear that in routine surgery, manual irrigation using 4000 ml of saline would be too time-consuming and laborious. Operating the aircraft tail combined with the pulsed irrigation is much simpler. Pressure causes the fluid to flow at a certain frequency and shooting force. The debris and bacteria in the joint cavity are separated from the tissue by the oscillating action of the pulsed water flow. During irrigation, the irrigation solution is drawn out through the aspiration channel. The total irrigation time in the CASS group was 6.9 ± 0.8 min, which was greatly reduced compared to that of the conventional group. Furthermore, the more irrigation solution used, the greater the reduction of irrigation time.
This study had several limitations, including the small sample size and insufficient postoperative follow-up time. In the future, a randomised controlled study based on a larger sample should be performed. Additionally, 4 L irrigation would be too time-consuming and laborious in routine surgery. We would recommend that 1–2 L of irrigation fluid would be more suitable for efficient removal of bone debris during tibial IMN. The most appropriate amount of irrigation needs to be determined in further studies.
Conclusion
This study demonstrated that the CASS system provides several advantages, including simplicity in the positioning of the protective sleeve, stability of the sleeve after insertion, minimal articular cartilage damage, convenient intraoperative irrigation, and shorter surgical times. This novel and practical improvement may bring about beneficial outcomes for tibial shaft fractures using the suprapatellar approach during intramedullary nailing, especially for the treatment of smaller patients with tibial shaft fractures.
Acknowledgements
Not applicable.
Funding
Not applicable.
Availability of data and materials
The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.
Ethics approval and consent to participate
This study has been approved by the Ethics Committee of the First People’s Hospital of Kunshan (NO. 20150512). Written consent was obtained from all participants in the study.
Consent for publication
Not applicable.
Competing interests
The authors declare that they have no competing interests.
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