Low trochanteric fractures in the presence of knee arthroplasty: The role of intermediate length cephalomedullary nail

INTRODUCTION

Intermediate-length (235–240 mm) cephalomedullary nails (ILCMNs) have been developed as alternatives to short and long cephalomedullary nails (CMNs) in trochanteric fractures to counterbalance their potential benefits and downsides. While providing more nail length distal to the locking screw compared to the short nails (SNs), intermediate nails employ the same distal locking screw location and targeting device as SNs. This facilitates the distal locking screw’s easy insertion and offers extra fit distal to the femur’s isthmus, which may be necessary for some fracture types that extend far distal to the lesser trochanter level.^[1]

While the presence of long-stemmed total knee arthroplasty (TKA) makes the utilization of long femoral nails impossible, the presence of unstemmed TKA may potentially interfere with or be complicated after using long nails (LNs).^[2] Despite several retrospective studies reporting on the outcomes of ILCMNs,^[3,4] no reports highlighted their specific utility in cases with trochanteric fractures in the presence of TKA. This study aims to report our single institution experience and outcomes of the intermediate length, 235 mm CMNs for cases of low trochanteric fractures in the presence of stemmed or unstemmed TKA, where SNs were not used due to the fracture configuration, and LNs were not used due to the presence of TKA.

MATERIALS AND METHODS

After Institutional Review Board approval, we reviewed 2834 proximal femoral nailing cases performed at our institution between 2007 and July 2024, using our selection criteria to extract the relevant cases.

The study included cases with low trochanteric fractures (AO/OTA 31A2.2, A2.3 and A3), those with a preceding TKA and received intermediate-length, 235 or 240 mm proximal femoral nail. We excluded cases that did not complete a minimum of 6 weeks of radiographic follow-up.

A total of 9 cases (9 patients) met the inclusion criteria. One case was excluded due to incomplete follow-up, leaving 8 cases (8 patients) with complete data for inclusion in this study. Patient demographics, notes, and all pre-operative and post-operative radiographs were individually assessed to extract all relevant data. Time until radiographic healing, the last available clinical and radiographic follow-up dates, and any complications were recorded. In all cases, the 130° TFN-Advanced (DePuy Synthes Trauma) 235 mm (lock-short) nails were used based on the surgeon’s pre-operative or intraoperative decision for cases with trochanteric fractures in the presence of distal TKA (five stemmed, three unstemmed) as an alternative to short or long CMNs. In all cases, the fracture configuration made SNs an improper choice as per the surgeon’s decision (six cases had a reverse obliquity, AO/OTA 31A3 fracture type, and two had low intertrochanteric, AO/OTA 31 A2.3 fracture with broken lateral proximal femoral cortex).^[5] As for the LN choice, the presence of a stemmed TKA renders the utilization of a LN not possible, while in the cases that had an unstemmed TKA, the surgeon decided to use ILCMN to avoid any potential interference with the TKA femoral component and any probable meddling with a future revision.

RESULTS

Radiographic outcomes

No intraoperative complications were recorded. No nail jamming occurred, and all nails were successfully inserted below the end of the distal isthmus after appropriate reaming. Fracture union was noticed at a mean of 13.2 weeks (6.4–23.9) [Figures 1-3].

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Figure 1:

(a and b) Immediate post-operative radiographs after open reduction and internal fixation using intermediate length proximal femoral nail with bridging plate for a 73-year-old female who sustained a low intertrochanteric fracture (AO/OTA 31A2.3) involving the proximal femoral lateral cortex, in the presence of a stemmed revision total knee arthroplasty that was inserted 1 month before. (c and d) 2-week follow-up radiographs showing maintained reduction. (e and f) 3-year follow-up radiographs showing fracture consolidation and maintained reduction.

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Figure 2:

(a-c) Plain radiographs of an 84-year-old male who sustained an intertrochanteric femoral fracture due to a fall. (d-g) Intraoperative C arm radiograph showing reduction with bridging fixation. The purpose of bridge plating is just to dissipate the stress riser at the end of the two opposing two intramedullary implants and not for fracture fixation. Consequently, the surgeon felt that plate fixation on either side of the nail could be sufficiently achieved with a single screw and cerclage wire. (h-j) Immediate post-operative radiographs. (k-n): 3-month follow-up anteroposterior and lateral radiograph showing fracture healing and stable fixation.

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Figure 3:

(a) Plain hip radiograph of a 90-year-old female presented with AO/OTA 31A2.3 trochanteric fracture. (b and c) The patient also had a loose, malrotated total knee arthroplasty (TKA). (d) Immediate post-operative hip radiograph and (e) 8-week post-operative plain hip radiograph showing fracture healing after insertion of intermediate-length cephalomedullary nails (ILCMN). The surgeon opted for intermediate-length cephalomedullary nails rather than long cephalomedullary nails to avoid any potential interference with the TKA, which would potentially require revision.

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DISCUSSION

This is a retrospective series of 8 cases with trochanteric fractures in the presence of TKA that was surgically managed with the 235 mm ILCMNs. After a mean follow-up of 52.3 months, all the cases achieved full fracture healing and none had implant failure, infection, or required revision for any cause.

The choice of nail length in intertrochanteric fractures (AO/OTA 31 A1-3) is still debatable and dependent on several variables, such as the fracture’s nature, the bone’s quality, and the surgeon’s preference.^[7] Due to their shorter surgery duration, relative ease of distal interlocking, less blood loss, and potentially lower costs, SNs (170–200 mm) are commonly utilized.^[7,8] However, in many cases such as those with large femoral medullary canals, fractures with inadequate proximal lateral femoral cortex,^[5] osteoporosis, pathologic fractures, fracture in patients with multiple falls,^[9] and trochanteric fractures with subtrochanteric extension (AO/OTA 31 A2.3 and A3)^[10] where SNs could not provide adequate fixation, LNs (300–480 mm) are more appropriate.

Conversely, potential drawbacks of LNs include lengthening the surgical procedure, necessitating more reaming, increased blood loss, raised costs, more difficult freehand distal locking insertion, and the potential mismatch between the nail and femoral shaft bow.^[1]

ILCMNs have gained increasing popularity. They were intended to provide an equally simple surgical technique as SNs with more stability afforded by the distal femoral fit. Since their introduction, several studies^[3,11] compared their outcomes to the more popular short or long CMNs. The findings of these studies suggest overall comparably good clinical and radiographic outcomes. Despite this, Enns et al.^[4] reported a high incidence of proximal fixation cutout with ILCMNs, which may be attributed to the older nail designs or the use of helical blades rather than the nail length.

In this study, ILCMN has been utilized for a specific indication, where a pre-existing TKA limited the use of long CMNs and fracture configuration made SNs improper options. In these cases, ILCMN was found to be the most appropriate option due to the easier surgical technique and, more importantly, to avoid interfering with the distal implants.

The evidence behind the concept of bridging or overlapping fixation between two implants remains lacking. CampilloRecio et al.^[12] recommended using prophylactic minimally invasive plate osteosynthesis between 2 intramedullary femoral implants (stemmed arthroplasty) to decrease the risk of secondary inter-prosthetic fracture given the increased stress risers and the decreased strength on such occasions. In our series, we have utilized bridging in 4 out of 5 cases that had a stemmed TKA, which was decided to be the standard of care in our hospital given the emerging, scarce evidence in this regard. The case that did not receive bridging was one of the first cases presented on this rare occasion.

CONCLUSION

Considering the results of the current study, the intermediate length, 235 mm nails could provide adequate and safe fixation and good outcomes in cases of proximal femoral fractures in the presence of TKA. Bridging between the nail and a distal intramedullary implant may be utilized to protect the inter-prosthetic bone from the increased stresses and potentially decrease the potential fracture risk. Larger studies are required to provide stronger evidence.