Abdominal Pain in a Female Runner

INTRODUCTION Muscle strains and partial tears are a common injury experienced in many different types of athletic activities. The usual treatment for these involves activity modification and physical therapy (PT). This treatment regimen frequently is effective and leads to sufficient improvement. For recalcitrant cases involving abdominal muscle injuries, such as described in this case, ultrasound-guided injection of platelet-rich plasma (PRP) offers a potentially effective treatment option. CASE PRESENTATION A 41-yr-old female runner presented to our sports medicine clinic with a 6-month history of right-sided abdominal pain. The pain began during an abdominal workout, when she felt a "pop" in her abdomen to the right of her umbilicus. She subsequently noted a small bulge in that same area but did not recall any discoloration or bruising. The pain was localized, nonradiating, cramp-like, and worse with activity. During the following weeks, she refrained from abdominal exercises and her usual activities of running and yoga. She took over-the-counter ibuprofen intermittently over the first couple of weeks after the injury but stopped because she did not feel that it was helping her symptoms. She then began a self-directed home abdominal rehabilitation program and noted some improvement of her pain at rest. However, she continued to have a similar cramp-like pain while attempting to run or practice yoga. The patient presented to her primary care provider 3 months after the initial injury. A complete abdominal ultrasound was ordered and showed no abnormalities. She was then referred to our sports medicine clinic for further evaluation and treatment. Upon review of systems, she denied any change in bowel habits, nausea, vomiting, or urinary symptoms. She was having regular menstrual cycles and her weight had been stable. She denied any history of other previous abdominal injuries or pain. She had no other pertinent past medical history, and her only medication was oral contraceptive pills. Her physical exam showed a woman who was well appearing, fit, and appropriate weight. Her abdomen showed no visible distension, bulge, ecchymosis, or defect. She had normal active bowel sounds. Her abdomen was soft with focal tenderness to palpation to the right of the umbilicus extending approximately 1 cm above and below. There was no palpable nodule or defect and no rebound or guarding. She was able to elicit the pain by engaging the abdominal muscles. To aid in our diagnosis, a musculoskeletal ultrasound was performed. This demonstrated a focal hyperechogenic area of obscured normal muscle architecture in the rectus abdominis muscle measuring approximately 1.5 × 3 cm, corresponding to the area of tenderness on physical exam and consistent with disorganized myofibrotic scar tissue without neovascularity (Figs. 1 and 2). This was compared to the contralateral side - which showed normal rectus abdominis muscle architecture - at the same cranial-caudal level. Normal active intestinal peristalsis was observed deep to the muscle layer walls.Figure 1: Musculoskeletal Ultrasound image of right Rectus Abdominus muscle strain at the level of the umbilicus showing myofibrotic scar tissue. The Ultrasound probe is oriented trans to the rectus muscle.Figure 2: Musculoskeletal Ultrasound image of right Rectus Abdominus muscle strain at the level of the umbilicus showing myofibrotic scar tissue. The Ultrasound probe is oriented long to the rectus muscle.Her history, physical examination, and musculoskeletal ultrasound all were consistent with a diagnosis of a chronic rectus abdominis muscle strain with degenerative appearing fibrosis. TREATMENT Treatment options and alternatives were discussed in detail with the patient. She declined activity modification alone, as she had already tried weeks of abstaining from yoga, abdominal workouts, and running, without improvement. She was offered a course of formally structured PT focused on the rectus abdominis muscle. Once again, though, she felt that she had been pursuing an aggressive home rehabilitation program for the preceding months and had not experienced any appreciable difference in her symptoms. We presented a third treatment option to the patient - regenerative injection therapy with PRP directed to the scarred rectus abdominis muscle. The potential risks of the procedure were reviewed with the patient in detail, including failure to relieve her symptoms, formation of additional scar tissue or calcification, infection, neurovascular injury (unlikely at this site), and injury to intraabdominal viscera, especially the bowel. Because this is a relatively new and novel treatment option for muscular injuries, there was insufficient evidence in the literature to offer a reliable prognosis for after the PRP therapy. After considering these options, the patient elected to proceed with musculoskeletal, ultrasound-guided injection of PRP. She was instructed to continue abstaining from nonsteroidal antiinflammatory medications and was scheduled for the procedure the following week. DISCUSSION OF THE PRP THERAPY Blood (52 mL) was obtained from the patient via antecubital venipuncture with a 17-gauge needle into a 60-mL syringe containing 8 mL of ACD-A anticoagulant. The whole blood was then spun in a specially designed centrifuge (Magellan Platelet Concentrating System) at 3200 rpm for 15 min to separate the blood into PRP, platelet-poor plasma (PPP), and packed red blood cells. Once separated, the platelets in the PRP fraction were resuspended, resulting in 3 mL of PRP with an estimated concentration of 12 times the physiologic platelet concentration of the baseline autologous blood. The skin overlaying the affected area was cleansed with betadine and covered with sterile gel. The area of myofibrotic scar in the right rectus abdominis was identified sonographically with the GE Logiq e Ultrasound System using a 12L straight probe. The area of pathology was anesthetized under ultrasound guidance with 3 mL of 1% Lidocaine without epinephrine via a 22-gauge, 1.5-inch needle. With the probe oriented trans to the rectus abdominis muscle, the needle oriented long to the probe and approaching from lateral to medial, percutaneous myofibrotomy with 30 needle fenestrations was performed throughout the area of degenerative scar. Subsequently, 3 mL of PRP was injected throughout the injured area. Careful visualization was maintained throughout the procedure to ensure accurate needle placement in the scar tissue and an adequate safety margin to avoid penetrating through the muscle layers to the underlying bowel (Fig. 3). There were no complications, and the patient tolerated the procedure well.Figure 3: Ultrasound guided needle fenestration of the Rectus Abdominus myofibrotic scar tissue.Postprocedure care was discussed with the patient in detail. She was told to expect increased soreness and pain over the next few days and was instructed not to take any antiinflammatory medications because this would inhibit the inflammatory cascade intentionally initiated by the PRP injection. The patient was given a prescription for acetaminophen-oxycodone for pain control to be taken if Tylenol® was not sufficient. She was instructed to refrain from any rigorous abdominal exercises for the next few days to minimize extravasation of the PRP from the target area. After a few days of rest, she was instructed to resume her abdominal rehabilitative exercises, as well as her daily running and yoga as tolerated. Follow-up was arranged 4 wk after the procedure to assess the patient's response to treatment and decide whether a repeat procedure was indicated. The patient was contacted by phone and reported significant improvement in her symptoms. She had no pain in the course of her day-to-day activities and had returned to her running routine. Given the response to the initial PRP treatment, the patient opted not to undergo any further PRP treatments. Postprocedure, 6 months later, she continues to be pain-free with all activities. PRP BACKGROUND AND DISCUSSION PRP injection therapy has been in use for more than 20 yr in a variety of clinical applications, from maxillofacial and cardiothoracic surgery to plastic surgery and wound healing (9). In recent years, PRP injections have been used increasingly for the treatment of a range of musculoskeletal injuries - most frequently, chronic, nonhealing tendon injuries such as plantar fasciosis, Achilles tendinosis, rotator cuff tendinosis, patellar tendinosis, and lateral epicondylosis. The rationale for PRP injections in the treatment of chronic soft tissue injuries is based on reports of pathological samples demonstrating angiofibroblastic degeneration, rather than inflammation as traditionally thought (6). Conversely, it is thought that the lack of inflammation, which represents a crucial first step in the healing process for soft tissue injuries, begins a cascade of maladaptive processes that lead to degeneration. The aim of PRP injections is to elicit a localized inflammatory response in the injured degenerative tissue, thereby inducing the healing process enhanced by the added concentrated platelets and other humoral factors. Storage granules within platelets contain a number or growth factors - such as platelet-derived growth factor, transforming growth factor, vascular endothelial growth factor, epidermal growth factor, and fibroblast growth factor. These growth factors play key roles in the healing of soft tissue injuries, including the removal of necrotic injured tissue and the recruitment of cell lines and other factors involved in regeneration and remodeling. Several aspects of PRP therapy require further study to determine the optimal procedure protocol. Among these is the ideal amount of platelet concentration, which has not yet been determined. The usual protocol is to concentrate the platelets to between 4 and 12 times the baseline physiologic platelet concentrations. It is uncertain whether greater concentration causes any harm. Another topic of debate is whether to introduce the PRP with percutaneous needle tenotomy, or as in this case, myofibrotomy. This involves perforating the target tissue, usually on the order of 20-60 times. One of the main advantages of soft tissue fenestration is thought to be increased irritation, enhancing the inflammatory and healing cascade. A disadvantage of tenotomy is more pain and tissue injury, and causing this additional injury has not yet been shown to improve effectiveness over PRP alone. There also is no set consensus on postprocedure medications and activities. It generally is accepted that antiinflammatory medicines should be avoided; the procedure is designed to cause inflammation, and taking an antiinflammatory would seem counterproductive. It also is generally accepted that vigorous activity should be avoided in the first few days following PRP injections to prevent the extravasation of the PRP from the injected tissue. Follow-up protocols vary widely on whether and how often to repeat the PRP procedure. Most providers of PRP therapy recommend following up from 3 to 6 wk after the initial treatment to ascertain the patient's response and consider repeating the procedure should there be inadequate improvement. Some are repeating the procedure in excess of four times. This lack of standardization and consensus in PRP therapy is due to the limited number of studies on the use of this treatment in soft tissue injuries. Existing studies are either animal studies or case controls with small numbers. An animal study by Aspenberg and Virchenko reported greater maturation in tendon callus and increased force to failure when PRP was used to augment rat Achilles tears (2). A study performed with human subjects by Mishra on PRP use in chronic elbow tendinosis showed that 93% of 15 patients had a significant recovery in pain at follow-up ranging from 12 to 38 months, and 99% returned to previous activities (7). A larger prospective, double-blind trial of 100 patients comparing PRP with cortisone for the treatment of lateral epicondylitis is underway by Gosen and colleagues (4). A study of nine patients with plantar fasciitis by Barrett and Erredge showed that six had complete pain relief at 2 months (3). The use of PRP during surgical tendon repair also is under investigation. Anitua and colleagues found faster recovery in athletes undergoing PRP-enhanced Achilles tendon repair (1). The PRP-treated athletes had earlier return of range of motion and resumed training activities in less time than the control patients. In rotator cuff repairs, the use of PRP was shown to decrease the time to recovery of full passive range of motion by Randelli and colleagues (8). There are even fewer PRP studies in the treatment of injured muscles. A study by Hammond et al. showed improvement in muscle function in rat models with PRP injections compared with no treatment (5). Another study in rat gastrocnemius contusions treated with concentrated platelets showed increased satellite cell activation and myofibril width (11). There are, however, currently no randomized controlled trials published on the use of PRP in humans for muscle injuries. There was a small study from 2005 showing an acceleration of functional restoration of injured muscles treated by ultrasound-guided injection of PRP in elite athletes (10). These athletes returned to full strength in as little as half the expected recovery time. Despite the paucity of randomized controlled studies on the use of PRP in tendon and muscle injuries, the existing research does show some promise. Since the pathophysiology of chronically injured muscles and tendons is now demonstrated to be tissue degeneration and maladaptive changes leading to disorganized and biomechanically inferior tissue architecture, the efficacy of a treatment that introduces inflammation and growth factors, like PRP injection therapy, seems very plausible. While more study clearly is needed in this area, the outcome in this particular case demonstrates a promising novel treatment for muscle injuries recalcitrant to conservative therapy and may indicate a helpful treatment for a range of musculoskeletal injuries.