Case report: Prevention of an above-knee amputation

Editorial series sponsored by Zimmer MedizinSystems

In September 2020, a 72-year-old male underwent a right total knee replacement after an unsuccessful trial of hylan G-F 20. He tolerated the procedure well and progressed in physical therapy (PT).

By January 2021, his knee was infected with Cutibacterium acnes and required extensive washout and implant knee replacement. This was followed by six weeks of IV rifampin via a PICC line into the right atrium of the heart.

This regimen was unsuccessful, so the patient underwent removal of the implants, insertion of antibiotic spacers and another PICC line. When joint fluid was synovasure negative and other infection indicators had normalized, the patient was replanted with another permanent total knee. During the gait cycle, the right leg collapsed during the left leg swing phase despite aggressive PT. In September 2023, the surgeon recommended scar tissue debridement and replacement of the tibial plateau acrylic implant. Subsequent to this fifth surgery, the patient returned to PT, strength training the right quadricep and gastrocnemius-soleus complex which had both severely atrophied. He also tried increasing body weight while supported by a sling from the ceiling.

By December 2023, the patient exhibited no discernable increase in ambulatory ability since his first surgery. Over three years, the patient attended 258 PT appointments with little or no improvement. He relied on a recliner and used a wheelchair for mobility. This was the picture of an otherwise healthy 75-year-old. His time out of the chair was solely for trips to PT or to see the surgeon. The knee remained flexed at approximately 30 degrees. His surgeon recommended an above-knee amputation with a prosthesis if the patient wished to regain even a modicum of quality of life, noting the above-knee amputation would result in a greatly decreased five-year survival rate similar to some cancers.

Arthrogenic muscular inhibition and patella baja

After the surgeon suggested above-knee amputation as an option, the patient took a more aggressive role in his future, discovering arthrogenic muscular inhibition (AMI). AMI involves inhibition of the vastus medialis obliquus (VMO) muscle and extension deficits due to hamstring contracture, which can lead to patella baja, a condition where the patella is below its normal position, resulting in a hard endpoint when extending the leg.

Degrees of involvement were classified from Grade 0 to Grade 3, including a video describing the physical exam used to classify each patient’s deformity. Grades 1 and 2 of the condition respond well to exercise, restoring normal extension and muscle strength. In Grade 2b, the VMO must be activated or gains in therapy will be lost once discontinued. Grade 2b requires up to a year of therapy with emphasis on waking up the quadriceps muscles, specifically the VMO with biofeedback and electrical stimulation. If Grade 2b does not respond to therapy, surgery may be necessary, including posterior arthrolysis of the knee joint capsule and patellar tendon lengthening. These procedures are fraught with risks, including complete rupture of the tendon and knee paralysis. Hence, noninvasive therapy modalities are preferable to invasive procedures where complications can easily arise.

The treatment plan

This patient was treated with Zimmer MedizinSystems’ emFieldPro high energy inductive therapy (HEIT) device on the quadriceps, specifically on the VMO, four times per week for 20 minutes, increasing contraction intensity as tolerated. Hypertrophy was substantial, gaining almost two inches in size. Circumference was not considered a parameter for success, but the study suggested a comparison of the not affected limb to the affected leg.¹ The strength gain was approximately 50% in the four months the patient was treated with the emFieldPro HEIT device. The patient was treated with the device on the contralateral side and included bilateral gastrocnemius-soleus muscles, anticipating a return to normal physical activity.

The patient was considered a stage 3 AMI when he began therapy and by April 2024 was still hitting a rigid endpoint approximately 20 degrees from full extension. He was also treated with the Zimmer MedizinSystems’ enPuls extracorporeal shockwave therapy (ESWT) device for the patellar tendon, the posterior knee capsule and biceps femoris tendon, which remained contracted and partially responsible for maintaining a rigid endpoint. In one month, he made remarkable gains in the patella’s position, but it was still engulfed in scar tissue and in a baja position. The biceps femoris tendon became significantly more flexible and released from its spastic condition. He received enPuls ESWT three times per week alongside emFieldPro HEIT. ESWT is contraindicated for patients on anticoagulants, such as Coumadin^®, Eliquis^® or Xarelto^®. This patient, on Eliquis^® for chronic atrial fibrillation, experienced no bleeding in area treated with the enPuls ESWT device. Literature reveals anticoagulants require extra caution regarding possible bleeding. Once an injury is incurred, there will be more bruising before hemostasis is achieved.

Five months of emFieldPro HEIT and one month of enPuls ESWT resulted in significantly more gains in AMI and patella baja than over three years of conventional PT, including electric nerve stimulation. Evaluation of the VMO muscles bilaterally revealed that affected limb was only 15% smaller than the unaffected limb and extension was measured to be 12 degrees.

emFieldPro HEIT

emFieldPro HEIT stimulates cellular signaling pathways, translating electromagnetic signals into biological signals at the cellular level. This process stimulates nerves, muscle fibers and blood vessels through growth factors like fibroblast growth factor, vascular endothelial growth factor and bone morphogenetic proteins. HEIT also stimulates the release of endorphins, reducing pain perception and restoring the normal resting potential of cell membranes, which normalizes electrolyte exchange and supports cellular functions, including energy production by mitochondria.^2,3 This therapy has shown impressive results for muscle stimulation and strengthening in deep tissues due to its high frequency and magnetic energy levels, which conventional PEMF units cannot achieve.⁴

enPulsPro ESWT

enPulsPro ESWT uses shock waves to induce microtrauma, promoting neovascularization and healing through the recruitment of stem cells and the release of growth factors. ESWT improves skin elasticity, increases collagen production and breaks up fibrous bands, releasing tissue. The mechanical energy from the shock waves transforms into a biological response through mechano-transduction, activating cellular structures and stimulating proteins essential for the healing process. ESWT has been shown to improve symptoms in conditions like osteoarthritis by inhibiting cartilage degeneration and promoting subchondral bone rebuilding.⁵

Conclusion

Early recognition of AMI and timely treatment with Zimmer MedizinSystems’ noninvasive emFieldPro HEIT and enPuls ESWT modalities can help avoid contracture of the patellar tendon. This reduces the chances of the condition progressing to a stage where above-knee amputation is necessary, significantly improving outcomes.

ROD TOMCZAK, MD, DPM, EdD, began his career in private practice and advanced to leadership roles at Des Moines University as surgical residency director and curriculum committee chair. He then served at The Ohio State University as chair of the problem-based learning curriculum and co-chair of the medical school curriculum committees. He also became the founding dean of medical universities in Belize, Curaçao and Saudi Arabia. To learn more, call 800-337-3576, visit zimmerusa.com or email info@zimmerusa.com.

References

Accessed September 30, 2024

1. Freychet B, et al. Arthrogenic muscle inhibition following knee injury or surgery: pathophysiology, classification, and treatment. Video Journal of Sports Medicine. 2022;2(3). Sage Journals. https://journals.sagepub.com/doi/10.1177/26350254221086295.
2. Stratton S. Role of endorphins in pain modulation. The Journal of Orthopaedic and Sports Physical Therapy. 1982;3(4):200-205. PubMed. https://pubmed.ncbi.nlm.nih.gov/18810127/.
3. Clement-Jones V, et al. Increased beta-endorphin but not met-enkephalin levels in human cerebrospinal fluid after acupuncture for recurrent pain. The Lancet. 1980;316(8190):946-948. PubMed. https://pubmed.ncbi.nlm.nih.gov/6107591/.
4. Paolucci T, et al. Electromagnetic field therapy: A rehabilitative perspective in the management of musculoskeletal pain: A systematic review. Journal of Pain Research. 2020;13:1385-1400. PubMed. https://pubmed.ncbi.nlm.nih.gov/32606905/.
5. Vinzenz A, Klemens T. Extracorporeal shock wave therapy: an update. EFORT Open Rev. 2020;5(10):584-592. PubMed. https://pubmed.ncbi.nlm.nih.gov/33204500/.