Level of Evidence: Prognostic Study, Level II-1 (retrospective study). See the Guidelines for Authors for a complete description of levels of evidence.
Intramedullary (IM) tibial nailing is an accepted fixation method for tibial shaft fractures.12 However, postoperative knee pain is a clinically important complication that can result in substantial patient morbidity.3,4,7 Knee pain reportedly affects from 56% to 67% of patients after tibial nailing.4,7,13 The pain after tibial nailing inhibits activities of daily living and does not improve with time or observation.5 Therefore, strategies to reduce the rate and severity of knee pain after tibial nailing are urgently needed.
The etiology of knee pain after tibial nailing has not been determined.15 We are unaware of reports of controllable surgical factors related to knee pain, although in three previous studies, investigators argued nail position was unrelated to knee pain.4,7,11
However, based on our clinical observations and experience, we hypothesized that nail prominence was related to knee pain after tibial nailing.
MATERIALS AND METHODS
We retrospectively reviewed 122 patients identified from our trauma registry with clinically and radiographically healed tibia fractures treated with IM nailing. The mean age of the patients was 45 years, and 45% had open fractures. The mean time between injury and outcome assessment was 20 months (range, 6-78 months). We performed a power analysis on our 70-patient cohort. A study with 70 patients would have 80% power to detect a factor that caused 35% difference in the proportion of patients with knee pain by the chi square test. A baseline rate of 50% of patients with knee pain was assumed.
We reviewed patients' charts for age, gender, type of fracture (open or closed), and followup. The operative reports were reviewed to determine the operative techniques including the incision type (medial parapatellar or transpatellar) and use of reaming (Table 1). Intramedullary nailing was performed with the patient supine and without traction. The extraarticular portal was established using the technique of the attending surgeon. Nails primarily were solid and were inserted with reaming to 1.5 mm over the desired size. All nails were statically locked. A Synthes titanium nail (Paoli, PA) was used in all cases with a 10°-Herzog bend. We did not remove any of the nails after union.
Surveys were mailed to the patients. All patients had healed fractures and had completed their final followup. Seventy of the 122 (57%) patients responded.
Knee pain was evaluated using several validated outcome measures (Appendix). The primary outcome measure was knee pain, which we assessed using VAS scores. In the survey (Appendix), patients were asked to rate knee pain at rest, kneeling, walking, and running.13 Overall knee pain was defined as the sum of a patient's VAS scores at rest, kneeling, walking, and running. Knee function was assessed using the Lysholm score, a 100-point, validated, reliable, and responsive outcome tool for functional assessment of the knee.8,9 As a point of reference, the mean Lysholm score after anterior cruciate ligament (ACL) reconstruction was 91 points.16 Subjective knee pain was measured with the question, “Do you have pain in the knee (Yes/No)?”
Postoperative radiographs were reviewed by one blinded reviewer (KS). Tibial plateau width was measured in millimeters using PACS digital radiographic software (AGFA, Weisbaden, Germany). The relative anterior and superior nail prominences were measured using the method described by Keating et al (Fig 1).7 We defined the nail-apex distance as the sum of the superior prominence and the anterior prominence (similar to the tip-apex distance used in hip fracture surgery).1
Statistical analysis was performed using SPSS statistical software (Version 10.0, SPSS Inc, Chicago, IL). We identified dichotomous factors associated with increased VAS knee pain scores using a Student's t test. For example, to test if reaming was associated with knee pain, the mean VAS scores for patients treated with and without reaming were compared using the Student's t test. We correlated linear variables (such as age) associated with increased VAS knee pain scores using the Pearson's correlation coefficient. We performed a linear regression analysis to control for multiple variables with overall knee pain as the dependent variable.
Thirty-four of 70 patients (49%) had knee pain (Table 1). Their mean Lysholm knee score was 68 points. The mean VAS resting pain score was 8.1 points and scores for walking were 25.1 points, kneeling 39.4 points, and running 54.9 points (Table 2). Subjective knee pain was more common (p < 0.05) in women and patients with a smaller (p < 0.008) plateau width. There were no correlations between knee pain and age, length of followup, reaming, or medial versus transpatellar insertion technique. Small diameter (≤ 9 mm) nails did not correlate with less knee pain.
Anterior prominence of the nail was associated (p < 0.008) with increased pain at rest (Table 3). Patients with superior prominence of the nail had increased (p < 0.03) pain with kneeling and walking. Overall knee pain correlated (p < 0.004; R 0.356) with the nail-apex distance. The nail-apex distance was not associated with other knee pain factors such as gender or tibial plateau width. If the nail was buried 1.25 cm in an anteroposterior radiograph and 1.25 cm in the lateral radiograph (ie, the nail-apex distance was 2.5 cm), patients had less (p < 0.037) severe knee pain, although pain was not eliminated (Fig 2).
Only the nail-apex distance remained associated (p < 0.009) with knee pain when controlling for age, gender, reaming, and tibial plateau width.
Knee pain after tibial nailing increased when the nail was left in a prominent position. Knee pain was more common in women and patients with a smaller tibial plateau width.
The main limitation of our study is its retrospective, observational design. Prospective studies are ideal for studying factors, but retrospective studies often provide a starting point for future studies. However, given the logic of burying a nail, it may not be ethical to perform a randomized, prospective study of prominent versus non-prominent nails. The relatively low response rate might bias patient selection because patients not responding might have either more or less knee pain than the cohort reported. Our study also was limited by the cohort size that limited multivariable analysis. However, using validated outcome measures allowed comparison with other studies. We were unable to correlate the starting portal position with knee pain severity because we lacked reproducibility of measurements. This analysis would be more accurately performed with CT scanning. We also were unable to reliably assess the role of reaming in the etiology of knee pain because the majority of patients had reaming. Ongoing prospective studies are needed to definitively answer this question.
Surgical damage, not the injury, plays a crucial role in the etiology of knee pain after nailing. In a randomized, prospective study of cast treatment versus IM nailing, Karladani et al reported 40% of patients who had IM nailing had knee pain and no patients treated with a cast had knee pain.6 A randomized trial of external fixation versus IM nail fixation found no knee pain in the external fixation group and 64% in the nailing group.2 Previous studies have focused on the parapatellar approach rather than the transpatellar approach. Toivanen et al, in a randomized prospective study, reported the rate and severity of knee pain were equal in patients who had parapatellar or transpatellar insertion.13 Vaisto et al found hamstring strength decreased in patients with knee pain after tibial nailing.15
Tornetta et al proposed that intraarticular injury to the cartilage or meniscus of the knee may be associated with knee pain.14 In a cadaver study of tibial nailing, 20% of knees sustained intraarticular damage, and an additional 30% of nails were adjacent to the menisci. In a followup study, McConnell et al identified the sweet spot for nailing was 22.9 mm, but it sometimes was as small as 12.6 mm.10 They defined the safe zone as a percentage of the tibial plateau width.10 Using this measurement, the error margin for a 10-mm nail could be as small as 2.6 mm before risking any articular structures.
Our data suggest intraarticular damage such as meniscal injury or surgical trauma play an important role in knee pain after IM nailing: women and patients with a smaller tibial plateau width (and therefore a smaller sweet spot) were at increased risk for knee pain. Although we found a mean Lysholm score of 68 points, the same mean score after ACL reconstruction has been reported as 91 points.16 Nail prominence was associated with knee pain as prominent nails were likely to be abutting or adjacent to the menisci.
Our findings contrast with those of Court-Brown et al,4 Keating et al,7 and Orfaly et al,11 who found no correlation between final nail position and knee pain. However, these studies used older nail designs with a wider proximal flair, and few nails were buried below the articular surface. We also recorded VAS pain scores, which are more discriminatory than the subjective assessments reported in those three studies. Superior prominence was associated with kneeling pain, and it likely was kneeling on a prominent nail that resulted in direct pressure against the hardware. Anterior nail prominence was associated with resting pain possibly because of irritating the patellar tendon.
Knee pain correlated with the nail-apex distance. Minimizing the nail-apex distance to less than 2.5 cm should reduce knee pain. However, burying the nail deep in the substance of the tibia may make subsequent nail removal (eg, exchange nailing) more difficult. Surgeons must balance these two extremes. Knee pain is multifactorial and a substantial source of morbidity. However, our data suggest surgeons can reduce knee pain after IM nailing by burying the tip of the nail, as reflected on lateral radiographs.
1. Baumgaertner MR, Curtin SL, Lindskog DM, Keggi JM. The value of the tip-apex distance in predicting failure of fixation of peritrochanteric fractures of the hip. J Bone Joint Surg Am
. 1995;77:1058- 1064.
2. Braten M, Helland P, Grontvedt T, Aamodt A, Benum P, Molster A. External fixation versus locked intramedullary nailing in tibial shaft fractures: a prospective, randomised study of 78 patients. Arch Orthop Trauma Surg
3. Court-Brown CM. Reamed intramedullary tibial nailing: an overview and analysis of 1106 cases. J Orthop Trauma
. 2004;18:96- 101.
4. Court-Brown CM, Gustilo T, Shaw AD. Knee pain after intramedullary tibial nailing: its incidence, etiology, and outcome. J Orthop Trauma
5. Dogra AS, Ruiz AL, Marsh DR. Late outcome of isolated tibial fractures treated by intramedullary nailing: the correlation between disease-specific and generic outcome measures. J Orthop Trauma
6. Karladani AH, Granhed H, Edshage B, Jerre R, Styf J. Displaced tibial shaft fractures: a prospective randomized study of closed intramedullary nailing versus cast treatment in 53 patients. Acta Orthop Scand
7. Keating JF, Orfaly R, O'Brien PJ. Knee pain after tibial nailing. J Orthop Trauma
8. Lysholm J, Gillquist J. Evaluation of knee ligament surgery results with special emphasis on use of a scoring scale. Am J Sports Med
9. Marx RG, Jones EC, Allen AA, Altchek DW, O'Brien SJ, Rodeo SA, Williams RJ, Warren RF, Wickiewicz TL. Reliability, validity, and responsiveness of four knee outcome scales for athletic patients. J Bone Joint Surg Am
10. McConnell T, Tornetta P3rd
, Tilzey J, Casey D. Tibial portal placement: the radiographic correlate of the anatomic safe zone. J Orthop Trauma
11. Orfaly R, Keating JE, O'Brien PJ. Knee pain after tibial nailing: does the entry point matter? J Bone Joint Surg Br
12. Schmidt AH, Finkemeier CG, Tornetta P3rd
. Treatment of closed tibial fractures. Instr Course Lect
13. Toivanen JA, Vaisto O, Kannus P, Latvala K, Honkonen SE, Jarvinen MJ. Anterior knee pain after intramedullary nailing of fractures of the tibial shaft: a prospective, randomized study comparing two different nail-insertion techniques. J Bone Joint Surg Am
. 2002;84: 580-585.
14. Tornetta P3rd
, Riina J, Geller J, Purban W. Intraarticular anatomic risks of tibial nailing. J Orthop Trauma
15. Vaisto O, Toivanen J, Kannus P, Jarvinen M. Anterior knee pain and thigh muscle strength after intramedullary nailing of tibial shaft fractures: a report of 40 consecutive cases. J Orthop Trauma
. 2004; 18:18-23.
16. Williams RJ3rd
, Hyman J, Petrigliano F, Rozental T, Wickiewicz TL. Anterior cruciate ligament reconstruction with a four-strand hamstring tendon autograft. J Bone Joint Surg Am
. 2004;86:225- 232.
Appendix 1. Questionnaire
© 2006 Lippincott Williams & Wilkins, Inc.
- Do you have a limp? (choose one)
- Slight or periodical
- Severe and/or constant
- Do you need a support device? (choose one)
- No support device
- Cane or crutch
- I cannot bear weight
- Locking-Which best describes you? (choose one)
- No locking and no catching sensations
- Catching sensations but no locking
- Locking occasionally
- Locked joint now
- Instability-Which best describes you? (choose one)
- No giving way
- Rarely, during athletics or other heavy exertion
- Frequently, during athletics or other heavy exertion
- Occasionally, in daily activities
- Often, in daily activities
- At every step
- Pain-Which best describes your level of pain? (choose one)
- Inconstant and slight, during heavy exertion
- Marked, during heavy exertion
- Marked, on or after walking more than 1 mile
- Marked, on or after walking less than 1 mile
- Swelling-Which best describes you? (choose one)
- On heavy exertion
- On normal exertion
- Stair-climbing-Which best describes you? (choose one)
- No problems
- Slight impairment
- One step at a time
- Squatting-Which below best describes you? (choose one)
- No problems
- Slight impairment
- I cannot squat beyond 90 degrees
- Impossible to squat