Managing pain in post total knee replacement plays a key role in successful outcomes

Osteoarthritis (OA) affects approximately one in 10 individuals and is equally prevalent in men and women, although there is higher prevalence in postmenopausal and obese women.1,2,3 Knee OA’s high prevalence is directly associated with a rising number of surgical interventions designed to reduce pain and increase mobility for patients (ie, total knee arthroplasty [TKA]).

Per Moffet et al’s 2004 study, “More intensive rehabilitation should be promoted in the subacute recovery period after TKA, to optimize functional outcomes in the first year after surgery.”4 Aggressive focus on active and passive knee extension is one of the most important components of postoperative early rehabilitation. Persistent TKA flexion contractures are difficult to eliminate once they have been present for more than 3 months.5

The most prominent outcome variable linked to OA and TKA is pain.1,6,7,8 The process for pain management that was applied in prehabilitation is the same process and rationale for postsurgical pain management.

Central sensitization plays an important role in postsurgical and post-traumatic pain.9,10 Postoperative pain is mostly nociceptive, which is pain perception following surgical insult.

Case Study

Patient P. Tella, male, aged 76 years old, presented post left TKA June 2, 2014, with multiple comorbidities. Postop at evaluation, P. Tella presented with postoperative pain, swelling, and bruising (typical of the recovery process following knee surgery). He also demonstrated muscle weakness, as would be expected with any surgery. All the cardinal signs of inflammation were present at the knee and its periphery. Different functional reporting tools (Functional Gait, PANAS, Pain Disability Index, Lower Extremity Functional Scale) were used at evaluation, at each visit, and at the discharge to determine efficacy of the interventions and to gauge progress at any stage of treatment.

A constant passive motion (CPM) machine11, such as those available through The Furniss Corporation, Grove City, Ohio, or the Optiflex by Patterson Medical, Warrenville, Ill, was used immediately postsurgery and continued at home x 2 weeks, 2 hours, three times a day (TID).

Bruising caused additional tenderness. As in prehabilitation, inflammation management will reduce pain. Each visit’s treatment included the use of photo-biostimulation over terminal sites in the inguinal region to open up the lymphatic flow to decrease inflammation from distal to proximal. Chattanooga, Tenn-based Richmar’s MedX 785-nm laser with 200 mW Gallium-Aluminum-Arsenide diodes on the EVO CM4 provided quick treatment of the terminal sites at 4 joules/cm2 or 20 seconds (the laser generates 1 joule every 5 seconds). This included use of superluminous diodes (SLD) at the terminal site post laser to coincidentally treat the terminal sites while applying ultrasound with the same Richmar EVO CM4 to reduce inflammation at the local site. The SLD infrared (870 nm) and the visible red (633 nm) provide similar outcomes to the laser to open up those terminal sites, but takes a little longer at 1 Joule per 45-second application (or a 3-minute treatment) to be applied every other day. SLD was applied each visit with the same parameters over the terminal sites. The market also includes Class IV lasers from Irvine, Calif-based Zimmer MedizinSystems, such as the OptonPro Class IV laser, which was recently released into the United States. Other devices include the Apollo Class IV cold laser from PHS Therapeutics, a division of Pivotal Health Solutions, Watertown, SD, and MR4 Super Pulsed Laser, Multi Raidance Medical, Solon, Ohio.

Coincidentally with photo-biostimulation, the 3 MHz sound head at 0.5 w/cm2 x 10 minutes (5-minute treatment for two times the size of the soundhead or, more specifically, the Effective Radiating Area for that soundhead) was used over the bruised and inflamed edematous, which will change cell membrane permeability by a process of acoustic streaming and stable cavitation. Richmar’s EVO CM4 ultrasound cued up the subthermal application with a single button using the hands-free Accusound applicator. Ultrasound will also modulate vasoconstriction; change lymphocyte adhesion properties of the endothelium; increase mast cell degranulation; increase phagocytosis by macrophage; increase production of growth factors by macrophages, resulting in calcium fluxes in fibroblasts, angiogenesis, proliferation of T-cells, osteoblasts, fibroblasts, and a number of proteins associated with inflammation and repair (IL-1, IL-2, IL-6, IL-8, interferon-?, fibroblast growth factor-b, vascular endothelial growth factor, collagen),12-25 as well as accelerate thrombolysis26-35; or reduce inflammation.

Use of the Richmar EVO CM4 will activate the appropriate parameters for the muscle pump using the following parameters: Russian Stimulation current, ramp time up 2 seconds, ramp time down 2 seconds, on time of 4 seconds and off time of 12 seconds, and treatment time of 10 minutes. With the limb elevated, electrodes are placed on the muscles on the quadriceps and the hamstrings with the intensity increased to a vigorous muscle twitch to wick away the inflammation to the aforementioned open terminal sites. All this is done coincidentally (biostimulation, ultrasound, and e-stim), saving time and increasing the quality of outcomes.

Fan cut therapeutic taping technique using Kinesio Tape from Kinesio Holding Corp, Albuquerque, NM, was applied with the base of the tape at the inguinal terminal site, and no tension along the length of the tape from the terminal site to surrounding the knee was utilized each visit to allow a passive means to carryover inflammation or edema management done in the clinic. P. Tella was instructed to elevate the lower extremity higher than heart level for an hour or two BID incorporating ankle pumps to manage the edema at home. The use of ice packs, such as those available through Battle Creek Equipment, Fremont, Ind, or cold packs by Strongsville, Ohio-based Roscoe Medical, can offer supplemental pain control through cold therapy, restricting the blood vessels and slowing the nerve impulse. To this end, ice pack use three to four times a day for about 10 to 20 minutes was instructed to reduce swelling and inflammation at the knee joint and surrounding tissue.

Per the pain modulatory mechanism of the “Gate Control” theory proposed by Melzack and Wall in 196536 and Bausbaum and Fields’37 proposed endogenous opiate theory, pain management was achieved with electrical stimulation (e-stim). Different frequencies activate central mechanisms to produce analgesia. Low-frequency e-stim activates ?-opioid receptors in the spinal cord and the brainstem, whereas high-frequency e-stim activates opioid receptors in the spinal cord and the brainstem.38-40 Any e-stim device, whether a clinic-based unit or any portable TENS unit such as the Richmar EVO CM4, the BioStim SD digital TENS, BioMedical Life Systems Inc, Vista, Calif, or SpectrumMicro-100, from Amrex-Zetron Inc, Paramount, Calif, would use the gate control or the endogenous opiate theory to result in similar outcomes, even though wave forms are different.

Photo-biostimulation with similar parameters as for inflammation management can be used but over acupuncture points in the arm at LI4, LI1, Tb5, and P6 as an effective means of managing pain anywhere in the body with the doses mentioned above. However, at each visit with P. Tella, the preset button on the Richmar EVO CM4 cued up Interferential current (IFC) quadpolar electrode placement (chained 100 Hz x 15 minutes and 2 Hz x 15 minutes, vector on fast 90o with an intensity at a slight motor twitch was utilized for pain management. Microcurrent (chained 30 Hz x 15 minutes and 0.3 Hz x 15 minutes with a subsensory intensity) could be utilized if the patient did not tolerate the sensation of IFC e-stim. Electrodes were applied to the same four acupuncture points at LI4, LI11, Tb5, and P6 to affect Melzack and Wall’s Gate Control Theory41 or Bausbaum and Fields42 endogenous opiate theory. A portable TENS unit with the same 100 hHz x 30 minutes and 2 pps x 30 minutes and a pulse width of 300 µsec was instructed to allow the means to carry over the positive pain-management results at home.42 He was instructed to use the TENS as often as he had pain to improve and maintain his pain threshold. Hyperalgesia or pain relief occurs whether an asymmetrical or symmetrical waveform is used. Different waveforms can be used to improve comfort but not to increase analgesic efficacy43, hence the efficacy of the TENS for home use.

Topical Creams and Patches

Topical creams and patches (first-generation transdermal delivery systems44) applied to the knee may help reduce pain. These products usually include active ingredients like capsaicin (also found in chili peppers), menthol, or salicylates. When absorbed through the skin, these ingredients are known to ease pain. Moab, Utah-based Sore No More, features the active ingredient menthol in its topical analgesic, Sore No More, which targets arthritis pain relief. Similar products for minor aches and pains are Flexall gels from Ari-Med Pharmaceuticals, Tempe, Ariz, and Sombra Professional Therapy Products, Albuquerque, NM, which offers pain-relieving gels comprised of warming and cool ingredients.

LidoFlex patches (nonprescription) were used at the periphery of the patella and changed out every 12 hours. P. Tella used the patches during waking hours at home as part of his pain-management regimen. Passive diffusion across the skin45-47 with transdermal patches eliminate frequent dosing administration and plasma level peaks and valleys associated with oral dosing and injections to maintain a constant drug concentration, and a drug with a short half-life can be delivered easily.

Second-generation transdermal delivery systems44 include those in which a substance bearing a charge is propelled through the skin by a low electrical current. Iontophoresis is defined as a means of use of a continuous direct electrical current to deliver therapeutically charged ions across the skin and into the systemic circulation.48-51 The IontoPatch, Patterson Medical, Warrenville, Ill, and the ActivaPatch, available through Gilroy, Calif-based ActivaTek Inc, exemplify technologies used in the delivery of iontophoresis that are available on the market. Phonophoresis would also be alternative to enhance the absorption of topically applied analgesics and anti-inflammatory agents through the therapeutic application of ultrasound. Neither of these techniques were used with P. Tella. Ultrasound applicator gels can be found through companies such as Parker Laboratories, Fairfield, NJ, which offers Aquasonic Clear and SCAN ultrasound gel.

Gaining strength in the muscles that support the joint in prehabilitation is as much of a requirement in post surgical management to help support the stability of the knee joint.

The reverse order of motor unit recruitment combined with external loading (muscle hypertrophy) imposed on stimulated muscles during training is likely responsible for the gains in muscular strength observed during muscle re-education training. Studies suggest 30% more force than maximum voluntary contraction.52 Studies also suggest that e-stim for muscle re-education produces lasting gains in muscle force through a short-term training regimen (approximately 30 training sessions).36,53-56

P. Tella was provided and instructed in the use of a portable combination TENS/Electrical Muscle Stimulator (Twin Stim II) unit with similar parameters completing the carryover of muscle re-education on the days he was not in the clinic. Kinesio tape application I strip six squares in length was applied from origin to insertion with 50% tension to facilitate the hamstrings and the quadriceps musculature at each visit (protocol was for 5 days of use, 1 day rest, and reapplication on the seventh day).

Altered Gait Biomechanics and Pain

P. Tella demonstrated altered gait biomechanics of reduced walking speed/cadence and decreased motion57 and increased lateral trunk lean58all of which can be a result of pain and inflammation. Tempe, Ariz-based Mobility Research’s LiteGait was utilized at each visit to provide better posture, better balance and weight bearing assistance while correcting upright postures appropriate for ambulation both over a treadmill and subsequent carryover to over ground ambulation. The evidence across animal and human literature suggests the number of repetitions for cortical reorganization through neuroplasticity is in the hundreds for the upper extremity59 and thousands for gait steps60 and with the LiteGait, P.Tella was able to attain 3168 feet first visit and by last visit 5280 feet. LiteGait enabled a partial weight bearing environment to allow the freedom for the therapist to facilitate weight shifting to correct P.Tella’s antalgic gait by off loading sufficiently the lower extremity associated with the painful post surgical knee initially. This allowed facilitation of foot placement and cueing appropriate patterns of walking. LiteGait through the support straps allowed progressive increase in weight bearing successively through each visit allowed distribution of supporting forces to meet P.Tella’s needs to become more symmetric in static posture and more functional in dynamic gait. LiteGait allowed an increased stretch of the hip flexors to facilitate the central pattern generators (automatic gait) and to integrate knee extension to increase painfree weight bearing in mid stance (often negated with lower extremity pathologies)61 but most of all allowing painfree repetitions so important in correcting a faulty gait pattern. LiteGait further allowed aerobic metabolism performed for gradually extended periods of time without decreased pain while limiting those gait deviations.62

Consistent use of the modalities combined with not only clinical units but also portable home units can help pave the way to faster outcomes. One piece of the treatment regimen without the other would not result in such positive outcomes in such a short period of time, but together as a whole, they can produce lasting outcomes. This program can be tweaked to result in similar outcomes with any joint dysfunction. PTP

Keith Khoo, PT, has been in practice since 1985. At the Scholl Center, Tulsa, Okla, he evaluates and treats movement disorders such as Parkinson’s disease and multiple sclerosis, as well as neuropathic patients, balance and vestibular disorders, pain management, and headache patients. Khoo has taught continuing education courses on modality applications for neuromusculoskeletal dysfunctions, vestibular and balance dysfunction, and Kinesio taping in the United States and abroad. For more information, contact [email protected]


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