Research Roundup: Pedicle Screw Insertion More Accurate with Robotic Assistance

The following is a roundup of three recently published medical studies that provide new insights into orthopedic procedures and patient outcomes:

Robot-Assisted, Fluoroscopy-Guided Pedicle Screw Insertion Methods Offer Similar Accuracy

Journal of Neurosurgery: Spine

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Using a robot-assisted technique is more accurate for inserting pedicle screws than the traditional fluoroscopy-guided pedicle screw insertion technique, but not statistically significantly so, according to researchers.

As part of a retrospective study, the researchers analyzed the charts of 95 patients who underwent lumbar spine surgery with posterior instrumentation for degenerative disease. Patients were split into two groups; group one comprised 55 patients and 244 pedicle screws inserted through the robot-assisted method, and group two comprised 40 patients and 163 pedicle screws inserted through the traditional fluoroscopy-guided method.

Accuracy of screw placement was graded using the Gertzbein-Robbins scale of A to E. Grades of A and B were considered clinically acceptable.

In group one, 83 percent of screws were graded as A and 7.8 percent of screws were graded as B. For group two, 79.8 percent of screws were graded as A and 7.4 percent screws were graded as B. The difference between the “clinically acceptable” screw placements in both groups was not statistically significant, according to the researchers (P = .19).



Condyle Location Influences Knee Flexion After TKA

The Journal of Arthroplasty

Translation kinematics effected knee flexion among patients who underwent total knee arthroplasty, with the location of the condyles having a major influence, according to study results.

Using a blocked, stratified, random sampling study design to reduce confounding and bias, researchers compared the kinematic patterns of 136 patients following total knee arthroplasty (TKA) with high postoperative knee flexion (HighFlex) with the kinematic patterns of 114 patients with limited knee flexion (LowFlex). The researchers collected kinematics using fluoroscopy and 2-D to 3-D registration for weight-bearing deep knee bend activities.

Compared with LowFlex patients, HighFlex patients were significantly more posterior in both lateral and medial condylar contact positions at full extension, which remained that way at all flexion angles. The researchers found the amount of contact point translation, axial orientation angle and axial rotation were similar for the two groups. However, LowFlex patients experienced significantly higher lift-off, indicating mid-flexion instability.



MRIShows High Sensitivity in Detection of Ligamentum Teres Partial Tears

Arthroscopy:The Journal of Arthroscopic and Related Surgery

MRI accurately uncovered partial tears of the ligamentum teres with high sensitivity and positive predictive value, according to recently published data.

Researchers studied 142 patients with a mean age of 35 years who received treatment for hip pain from 2010 to 2011. The patients underwent MRI followed by arthroscopic surgery, and ligamentum teres (LT) status (intact, hypertrophic, partially torn or completely torn) in both procedures was documented.

MRI accuracy for diagnosing partial LT tears was 64 percent. Sensitivity and specificity in the diagnosis of partial LT tears were 91 percent and 9 percent, respectively, and 78 percent and 32 percent, respectively, for diagnosing hypertrophic LT, according to the researchers. Positive predictive value was 67 percent, whereas negative predictive value was 31 percent.

“The diagnosis of LT tears as a cause of hip pain is a relatively new diagnosis,” the researchers wrote. “Although the overall treatment plan may not change based on MRI diagnosis, the status of the LT will allow the surgeon to plan for possible LT treatment.”