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The Evolution of InterSpace® Knee: A Case Review of the New InterSpace Knee Augmented Tibial Stem (ATS)

Clinical Contributor

Timothy van de Leur, MD
The Orthopaedic Institute
Ocala, FL

The InterSpace Knee has been a solution for surgeons for more than 20 years, and its extensive clinical data demonstrates its utility and effectiveness.1 Since its inception, the number of revisions has risen, and with that comes more infected cases. The complexities that come with managing infected revisions can be unpredictable, especially after multiple revisions. With this in mind, it is important for surgeons to have options when they tackle these difficult cases where patients present different anatomies and varying levels of bone deficiencies.

Clinical Contributor: Timothy van de Leur, MD
The Orthopaedic Institute, Ocala, FL

“Infection is a difficult problem to treat and work through with patients. Oftentimes, patients don’t understand the challenges and just want a normalcy that includes a reduction in pain, a return to mobility, and elimination of the infection. The InterSpace Knee system offers straight-forward sizing and trialing in the O.R., and to me, it has proven to be a simple and effective tool that has helped me help my patients return to some normalcy.”

“Over the last decade, I routinely formed and molded a stem to the distal portion of the InterSpace tibia and overcame the challenge of large defects with significant bone loss by adding more cement. Naturally, I am pleased with the new InterSpace Knee ATS and the option it gives me to add a stem, which makes up for larger bone deficiencies. The simplicity of the InterSpace Knee construct remains intact with the addition of the ATS as the intraoperative implant sizing options are easy to determine with the same trialing approach. I believe that adopting the ATS in infected revision cases is the next logical step to address a broader range of patients facing challenging deformities in the infection process.”

Case Review:

  • 67-year-old male with chief complaint of left knee pain. Severe arthritis with bone-on-bone arthritis, cystic changes, bone spurs, and osteophytes was observed. TKA was performed.
  • Two-month post-operative incision was clean, dry, and intact. Range of motion (ROM) was 5-125 degrees and films were normal. Patient was scheduled for 10-month follow-up visit.
  • Patient was seen in clinic four months post-operative with complaints of lower back pain and pain on operative knee. Patient had resumed golfing daily. Patient received epidural injections from Pain Management for back pain.
  • Patient returns five months post-operative with swelling and heat in operative knee; no drainage. Patient stated knee pain was not present prior to epidural injections administered two months prior for back pain. ROM was 0-120. ESR, CRP, and joint aspirate ordered for Synovasure study.
  • After one week, patient reported back with hot, red, tender, ecchymosis with preserved ROM in the knee. ESR and CRP were elevated, Synovasure showed positive alpha defensin and neutrophil elastase, and culture positive for Staph. lugdunensis. Antibiogram showed sensitivities to ciprofloxacin, clindamycin, erythromycin, lefocloxacin, rifampin, tetracycline, and vancomycin.
  • Patient was taken to surgery for incision and drainage (I&D) and placement of antibiotic spacer (InterSpace Knee with Augmented Tibial Stem (ATS)). Antibiotic beads left in the wound before closure.
  • Two-week follow-up from spacer implantation, the patient expressed a reduction in pain as a 7/10. The wound was clean, dry, and intact, and sutures were removed.
  • Films showed a well-fixed spacer, and patient demonstrated ROM of 0-90 degrees.
  • At latest follow-up, the patient was instructed to be diligent in continuing antibiotics and following up with Infectious Disease (ID). There were no obvious signs of infection, and patient appears to be on path for reimplantation.

Preoperative Images:


Lateral View, 5 Degrees

Standing

Intra-operative Sizing of InterSpace Knee with ATS:

Tibial Trialing with Femoral Measurement

Full Construct Trialing

Post-operative Films of InterSpace Knee with ATS:

Standing AP View

Lateral View, 5 Degrees

REFERENCES

  1. Data on file at Exactech, Inc.
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