Keywords
arthroplasty, replacement, knee - bone nails - intraoperative complications - orthopedic
procedures
Introduction
Total Knee Arthroplasty (TKA) is one of the most successful operations in orthopedics;
it is highly effective in relieving pain and improving function.[1] The occurrence of complications during TKA impacts the postoperative outcome and
the functional improvement of the patient. Pinaroli et al.[2] have described various intraoperative complications, which are mainly due to the
surgical technique chosen, and they include periprosthetic fractures,[3] tendon or ligament injury,[4] and nerve[5] or vascular[6] complications. In the present article, we report a case of an unusual complication:
pin migration into the femoral medullary canal during TKA. To the best of our knowledge,
this complication has not been reported before.
Case Report
The patient was a 72-year-old male who complained of pain and difficulty in walking
and climbing stairs for the previous 6 months. The pain increased considerably when
squatting and sitting on low seats, and was relieved only partially with non-steroidal
anti-inflammatory drugs (NSAIDs) and the local application of ice. Upon examination,
the patient had a fixed flexion deformity of 15° with further flexion of 125° associated
with crepitus and terminal movements, causing severe pain. Radiographs of the affected
knee confirmed the clinical findings and showed advanced tricompartmental involvement,
necessitating TKA. The patient was submitted to TKA under spinal anesthesia with the
use of a tourniquet. A midline skin incision was performed with a medial parapatellar
approach, and the joint was exposed, which reconfirmed the advanced tricompartmental
involvement. A posterior stabilized knee system was used sacrificing the posterior
cruciate ligament. The tibia was prepared first, followed by the femur. After the
distal portion of the femur was cut and the gap was checked in extension, a five-in-one
anteroposterior (AP) cutting block was placed and cuts were initiated. However, a
medial overhang of the cutting block was noted, hence it was shifted laterally to
prevent uneven condylar cuts. While doing so, the pins had to be shifted too, and
one of them was inadvertently hammered into the previously-created medullary canal
opening of the femur. Therefore, an attempt was made to retrieve the pin with the
help of an artery forceps, which was in vain, as it resulted in the pin getting pushed
further into the medullary canal. Then, pituitary rongeurs were used to circumvent
the depth issue; this maneuver also failed, as we could not reach deep enough to hold
on to the tip of the pin ([Figs. 1] and [2]). With no success in sight, C-arm fluoroscopy was employed to visualize the exact
position of the pin, which was far beyond the reach of the usual “grabbing” instruments.
An attempt was made to even “drop” the leg down, using gravity in the hope that the
pin would “fall down” the medullary canal. During this event, one of the operating
team members suggested the use of a laparoscopic instrument to remove the pin.
Fig. 1 Five-in-one femoral cutting block.
Fig. 2 C-arm fluoroscopy image showing the proximal migration of the pin.
Fortunately, our operation theatre complex is well equipped with general and laparoscopic
instruments. An extra-long laparoscopic grasper was used under fluoroscopy control
to locate, grasp, and remove the migrated pin ([Figs. 3], [4] and [5]). Once the migrated pin was removed, the TKA procedure was performed in the usual
manner. Postoperatively, the patient was informed about this intraoperative event.
The postoperative course in the hospital was uneventful, and the patient made a very
good functional recovery after the TKA.
Fig. 3 C-arm fluoroscopy image showing a pituitary rongeur falling short of the migrated
pin.
Fig. 4 C-arm fluoroscopy image showing a laparoscopic instrument holding the migrated pin
in the femoral medullary canal.
Fig. 5 The retrieved migrated pin.
Discussion
Intraoperative complications can occur during TKA procedure. Pinaroli et al.[2] analyzed the intraoperative complications of 1,624 patients submitted to TKA, which
included 69 fractures and ligament tears (3.8%), 40 fractures around the knee (2.2%),
and 28 tendons or ligament tears (1.6%). In the study by Agarwala et al.,[7] out of 3,168 primary TKAs performed between 2010 and 2017, 19 patients developed
intraoperative fracture, 15 in the tibia and 4 in the femur, and most fractures occurred
during cementing and final implantation (8 cases), followed by exposure and bone preparation
(6 cases), and trialing (4 cases). One fracture occurred at an unknown time during
the surgery. In the literature, there are many reports of pin-related complications
with the use of computer-assisted navigation.[8]
[9] Beldame et al.,[8] in a series of 385 TKAs, found an incidence of 1.3% (5 patients) of femoral fractures
at the site of the tracker pin. Kamara et al.[9] reported a complication rate of 0.16% (n = 5) per pin site in a total of 3,136 pin
sites in 839 patients. To the best of our knowledge, the present case report is the
first in the literature which describes this unusual complication of pin migration
to the femoral medullary canal. The operating surgeon needs to be very careful in
placing the five-in-one femoral cutting block, so as to ensure that the block is placed
in its designated place before initiating the cuts. Also, while pinning the five-in-one
cutting block to the bone, the surgeon needs to be aware of the position of the open
femoral medullary canal to prevent this avoidable error of migration of the pin.
