Long-Term Patient-Reported Knee Outcomes After Suprapatellar Intramedullary Tibial Nailing

Abstract

Background

Suprapatellar nailing of tibial fractures has not been shown to affect short-term knee outcomes, however long-term outcomes are unknown. The purpose of this study was to report long-term patient-reported knee outcomes after suprapatellar nailing.

Methods

Thirty-five adult patients with 37 tibial shaft fractures treated with suprapatellar nailing completed the Tegner-Lysholm Knee Score (TLKS) at an average of 5 years (range, 4–9 years) follow-up.

Results

The median TLKS was 98 (interquartile range, 85–100): Scores were considered excellent in 24 (68%), good in 3 (9%), fair in 3 (9%), and poor in 5 (14%). Based on patient responses, 28 (80%) patients did not have a limp, 32 (91%) ambulated without assistance, 22 (63%) were pain free, 29 (83%) had no knee instability, 30 (86%) endorsed no catching or locking, 27 (77%) could climb stairs with no issue, and 24 (69%) had no problems with squatting. Patients with poor/fair outcomes on the TLKS were more likely to have had a complication [3 (38%) vs. 1 (4%), difference 34%, 95% confidence interval 1–65%] and had no detectable difference in age, gender, open fracture, fracture classification, or worker’s compensation.

Conclusion

At long-term follow-up a majority of patients undergoing suprapatellar nailing had good/excellent knee outcomes. Poor/fair knee outcomes were associated with the development of complications.

Level of Evidence

III, Retrospective cohort study.

Introduction

Suprapatellar nailing has been widely adopted for the fixation of tibial shaft fractures as it allows for easier fracture reduction, better fracture alignment, and less fluoroscopy time [1–3]. Since the introduction of suprapatellar nailing there have been persistent concerns regarding articular damage to the patellofemoral joint secondary to the insertion of the nail, however clinical results have yet to demonstrate this [1, 3–7].

Outcome data extending beyond 12 months after suprapatellar nailing is limited and do not show increased rates of knee pain or arthritic changes compared to infrapatellar nailing [2, 3]. If this approach does result in cartilage damage longer-term follow-up may be necessary to detect increased rates of knee pain. The purpose of this study was to report long-term knee outcomes after suprapatellar nailing of tibial shaft fractures.

Materials and Methods

After institutional review board approval a chart review was performed to identify all patients who sustained a tibial shaft fracture treated with suprapatellar intramedullary nail at a level one trauma center between 2009 and 2013. We identified 148 tibial shaft fractures.

In brief, suprapatellar nailing was performed through a midline suprapatellar incision. A starting wire was then passed through the patellofemoral joint to achieve a starting point just medial to the lateral tibial eminence on the anteroposterior radiograph and just anterior to the articular surface on the lateral radiograph, with the wire parallel to the slope of the anterior tibia [8]. A protected cannula was then placed over the starting wire. A starting reamer was used, followed by sequential shaft reamers until reaching 1.5 mm over the desired nail diameter. The nail was then inserted and fixed proximally and distally with interlocking screws. After confirmation of reduction and hardware placement the insertion handle and cannula were removed from the knee. The knee was then irrigated with saline and closed in a layered fashion. Postoperatively patients were made weight bearing as tolerated with no restrictions in knee range of motion. Suprapatellar nails utilized included the Expert Tibial Nail (Depuy Synthes, Warsaw, IN) and the T2 Tibial Nail (Stryker, Kalamazoo, MI).

Patients who were non-English speakers or who had concurrent ipsilateral knee injuries were excluded. We successfully contacted and consented 35 patients with 37 tibial shaft fractures via telephone. The median patient age was 32 years (interquartile range, 26–53 years), 25 (69%) were male, and the average follow-up time was 5 years (range, 4–9 years). Open fractures were present in 10 (28%). Worker compensation was involved in 4 (11%) patients.

The Tegner-Lysholm Knee Score (TLKS), a knee-specific patient reported outcome measure used in multiple studies to evaluate knee outcomes after tibia nailing, was administered over the phone [2, 7, 9, 10]. In this scoring system, a score of > 90 is excellent, 85–90 is good, 65–84 is fair, and < 65 is poor. Patients were asked if they had undergone any subsequent surgeries to the knee, excluding proximal interlock screw removal, since the initial surgery. The medical record was reviewed for complications and reoperations.

Nonparametric statistical tests were used based on the presence of non-normally distributed data as determined by the Shapiro-Wilks test. Continuous data is as the median and interquartile range (IQR). The Wilcoxon rank sum test and the Fisher Exact test was used to compare continuous and categorical variables between groups, respectively. The difference in medians along with the 95% confidence interval (CI) between non-parametric continuous variables was calculated with the Hodges-Lehmann estimator. A p-value less than 0.05 was considered statistically significant. All analyses were carried out using JMP Pro version 14 statistical software (SAS; Cary, NC).

Results

The median TLKS was 98 (interquartile range, 85–100): Scores were considered excellent in 24 (68%), good in 3 (9%), fair in 3 (9%), and poor in 5 (14%). Based on patient responses, 28 (80%) patients did not have a limp, 32 (91%) ambulated without assistance, 22 (63%) were pain free, 29 (83%) had no knee instability, 30 (86%) endorsed no catching or locking, 27 (77%) could climb stairs with no issue, and 24 (69%) had no problems with squatting.

Patients with poor/fair outcomes on the TLKS, compared to those with good/excellent outcomes, were more likely to have had a complication, but had no detectable difference in age, gender, open fracture AO/OTA fracture classification, or worker’s compensation (Table 1). The confidence intervals were wide for all observed differences between these groups, therefore clinically significant differences cannot be excluded.

Table 1.

Comparison of patients with excellent/good versus poor/fair knee outcomes

	Excellent/good TLKS (≥ 85) (n = 27)	Poor/fair TLKS (< 85) (n = 8)	Difference, 95% CI	p-value
Age (years)	31 (26–53)	45 (27–53)	3, − 13 to 22	0.6
Female gender	9 (33%)	2 (25%)	− 8%, − 38 to 29%	1.0
Open fracture	7 (26%)	3 (38%)	12%, − 22 to 47%	0.6
AO/OTA classification	A: 19 (70%) B: 3 (11%) C: 5 (19%)	A: 5 (63%) B: 1 (13%) C: 2 (25%)		0.8
Complication	1 (4%)	3 (38%)	34%, 1 to 65%	0.03*
Worker’s compensation	3 (11%)	1 (12%)	1%, − 22 to 34%	1.0

Continuous variables are presented as median (interquartile range) and nominal variables are presented as n (%)

TLKS Tegner Lysholm Knee Score, CI confidence interval

*A p-value less than 0.05 was considered statistically significant

There were 4 (11%) complications, all secondary to osteomyelitis after open fracture. None of the infections involved the knee joint. All patients required operative debridement. Three patients underwent nail removal through an infrapatellar approach. Two of these patients required antibiotic spacer placement and had a poor TLKS (60 and 38, respectively). The third patient requiring nail removal had an excellent TLKS of 100. The fourth patient, who did not require nail removal, had a fair TLKS of 80.

There were five patients who had symptomatic interlock screw removal, all of which reported no knee pain and a TLKS of 100.

Discussion

Suprapatellar nailing of tibial shaft fractures has been increasingly adopted over the last decade with limited long-term follow-up. Insertion of a nail through the patellofemoral joint has raised concerns over damage to the articular surface [4–6]. This study found that at an average of 5 years after suprapatellar nailing 77% of patients had excellent/good knee outcomes. Poor/fair knee outcomes in this cohort were associated with the development of a complication, which included four patients with osteomyelitis that required debridement and removal of the nail in three patients.

The median TLKS of 95 observed in our study compares favorably with other studies looking at the short-term knee outcomes after suprapatellar nailing. Serbest et al. [10] performed a prospective study of suprapatellar nailing in 21 patients with a minimum of 12 months of follow-up and reported an average TLKS of 95. Arthroscopy performed after the procedure did not identify articular damage in any of the patients. Additionally, none of the patients endorsed anterior knee pain or functional limitations. Similarly, Chan et al. [2] reported an average TLKS of 98 in patients undergoing SP nailing at 12 months with no patients endorsing anterior knee pain.

Although long-term knee outcomes after suprapatellar nailing is unavailable, it is known for infrapatellar nailing; The incidence of knee pain after this procedure has been reported to be high, ranging from 30 to 69% with functional limitations being prevalent across studies [11–13]. Lefaivre et al. [7] collected outcome scores on 56 patients a median of 14 years after infrapatellar nailing and found 73% of patients had at least moderate knee pain. A prospective randomized control trial comparing transtendinous vs. paratendinous infrapatellar nailing at 3 years found that 67% vs. 71% of patients complained of anterior knee pain and had an average TLKS of 90 and 92, respectively.

Direct comparisons of long-term patient-reported knee outcomes after suprapatellar vs. infrapatellar nailing are currently not available. Chan et al. [2] did compare knee pain and TLKS between the two approaches at 12 months in a prospective randomized control pilot study of 41 patients and reported no difference in knee pain or TLKS, with scores of 86 and 98 in the infrapatellar and suprapatellar groups, respectively. This study that was not sufficiently powered to detect a minimal clinical significant difference (MCID) in TLKS between these groups. Based on the average (± standard deviation) TLKS observed in our study (87 ± 21) we estimate that the MCID in TLKS would be 10 points [14]. We estimate that 138 patients would be needed to detect a 10-point MCID in the TLKS between suprapatellar and infrapatellar nailing for a two-sided 0.05-level test with a power of 80%.

The findings of this study are limited by the lack of a control group and its reliance on phone survey information. As such, we are unable to comment on clinical or radiographic outcomes like range of motion or arthritic changes, and how this compares to infrapatellar nailing. We were only able to successfully contact and survey 35 patients due the inherent difficulties of contacting a trauma population several years after injury, which could also bias our results. Another limitation includes the lack of preoperative knee outcomes, however this is currently a limitation of all studies on this subject as pre-injury outcomes cannot be obtained secondary to the nature of trauma. Other factors that could result in knee pain, such a limb alignment, were also not evaluated, however the goal of this study was to obtain baseline TLKS scores in this patient population for comparison with data from the infrapatellar nail population. If suprapatellar nailing does result in increased knee pain, this group would expect to have higher rates of knee pain regardless of other factors. Finally, this study was underpowered to detect differences in variables that could affect knee outcomes scores as evidenced by the wide confidence intervals.

Despite this study’s limitations, it is the first study to report patient-reported knee-specific outcomes at long-term follow-up after suprapatellar nailing. This data is valuable because it can be compared against long-term outcomes after infrapatellar nailing, which is available in the literature. In addition, we were able to use this data to perform a sample size calculation that can be use for the development of future prospective studies comparing long-term knee outcomes after suprapatellar and infrapatellar nailing.

Conclusion

At long-term follow-up a majority of patients undergoing suprapatellar nailing had good/excellent knee outcomes. Poor/fair knee outcomes were associated with the development of complications that required revision surgery. The findings of this study allowed for the sample size calculation necessary for future studies to compare the long-term knee outcomes between suprapatellar and infrapatellar nailing.

Funding

None.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical standard

This article does not contain any studies with human or animal subjects performed by the any of the authors.

Informed consent

For this type of study informed consent is not required.