Exercise guidelines for the prevention of osteoporosis in postmenopausal women

by Jeslin Thomas

30% of postmenopausal women in the US were reported to have Osteoporosis, and at least 40% of these women will sustain one or more fractures during their lifetime. That’s a significant number to think about.  Fractures can lead to pain, disability, loss of activity tolerance, and functional independence. Also, after an initial fracture, individuals are 2x at risk for secondary fractures within that year.

While the disease is more common in women, men are also at risk for osteoporosis. Nonetheless, if you are diagnosed with this or are at risk of being diagnosed, it’s essential to know that our bodies are still incredibly adaptable. Countless research has shown that exercise is an EXCELLENT evidence-based tool to decrease modifiable risk factors for falls and fractures! Your bone is a dynamic tissue that responds to your body and external loads by changing its structure/strength and alters its mass. It does so to withstand any excessive loads that are likely to result in a fracture.

This systematic review highlights the following key points:

  1. Principle of Specificity: target specific areas of the body that are most susceptible to fractures: wrist, hip, and spine
    • Incorporating back extension strengthening exercises was associated with increasing spinal bone density.
    • High impact jumping exercise interventions 2-3x/week in post menopausal women were found to have a significant positive impact on the femur 12 months after it was performed. (We recommend discussing with a Physical therapist to find a strengthening program that’s right for you- our bodies respond differently based on our needs)
  2. Principle of Progressive Overloading: as your bone adapts to an exercise, it must be increased progressively (Ex: increase time spent, add more reps, add weights or resistance bands)
    • We recommend progressing your exercise once it starts becoming easier/every 2 weeks as a guideline.
  3. Principle of Reversibility: Any skeletal changes from exercise training will be lost once you stop it. Minimum dose to have a positive effect on your bones for the long term is 2 sessions per week.
    • For true physiological skeletal changes to occur, the exercise intervention must last over 12-18 months. Patients may see the greatest changes in their bone mineral density during the first 5-6 months of starting the program.

Research-based parameters:

      • Weight-bearing exercises 4-7x/week
        • Ex: sets of jumping 20-40 times, bounding, skipping, hopping, playing tennis, dancing, recreational gymnastics, or playing football
      • Challenging balance training for ~3hrs/week reduces falls by 39% and doing reactive or volitional stepping training reduces falls by 50%
        • Ex: leaning/reaching over your toes, being able to stand still despite any perturbations, stepping over surfaces, and walking on unstable surfaces.
      • Type of exercise: water-based exercise has been proven to reduce age-related bone loss at the hip and lumbar spine. Land-based exercises are better for improving your bone health overall.
      • Resistance training: maintains and helps to improve bone mineral density when performed at high-intensity loads.
        • Minimal requirements: 2 sets, 12 repetitions, at 70% of your maximal muscle strength. Performed 2-3 times per week.
        • The exercise has to be progressively increased over time, and it must target your large muscle groups. Ex: squats, lunges, hip abduction/adduction, and abdominal strengthening/Transverse Abdominis focus.

At Physical Therapy First, our clinicians are highly knowledgeable and trained to create a program that is tailored to your needs. If you are someone who is at risk or have been diagnosed with osteoporosis or low bone mineral density, you could benefit from an evaluation by one of our therapists to decrease any modifiable risk factors and maintain your physical health.

Reference:

Daly RM, Dalla Via J, Duckham RL, Fraser SF, Helge EW. Exercise for the prevention of osteoporosis in postmenopausal women: an evidence-based guide to the optimal prescription. Braz J Phys Ther. 2019;23(2):170-180. doi:10.1016/j.bjpt.2018.11.011

 

Spondylosis, Spondylolysis, and Spondylolisthesis: What’s the difference?

by Jeslin Thomas

It’s not as tricky as you may think. If you are curious or have been diagnosed with one of these, the therapists at PT First can help you out!

Spondylosis: refers to when you have degenerative osteoarthritis (OA) of the spine- this essentially means that the space between your vertebrae narrows as the protective cartilage that cushions the ends of the vertebrae wears down with age. With time, you may notice you have more of a flexed (forward bending) posture. Individuals suffering from this may experience lower back pain, leg pain, and/or numbness when standing or walking; symptoms may only seem to improve with sitting or lying down1.

Spondylosis

Spondylolysis: refers to a stress fracture defect in the pars interarticularis of the vertebrae (commonly found in the L4/L5 region). This is usually caused by repetitive stress or trauma at the Lumbar spine from strenuous activities involving excessive twisting/rotating or back bending (ex: gymnastics, dancing, wrestling, and football.). Symptoms may or may not be present initially, but as the injury progresses, these individuals may complain of pain as they bend backward or pain with general activities2.

Spondylolisthesis: often refers to the progression of a spondylosis injury, but it may also be congenital or idiopathic in nature. Spondylolisthesis is defined as the displacement of one vertebra over the vertebral body below it (commonly known as a “step off” or “slip” at the L5/S1 level); individuals may even notice the presence of a bump by the area of the slippage. There are 5 different grades of this slippage, and it’s defined by the extent to which the vertebral body has slipped:
Grade I: O-25%        Grade III: 50-75%        Grade V: > 100%
Grade II: 25-50%      Grade IV: 75-100%
Individuals with this may complain of localized pain that may come and go with certain activities, and this may be the most notable when bending backward or forward at the affected segment. They may experience radicular pain down to one or both legs as the vertebrae slides and causes compression of the nerve root below, tense hamstrings, loss of bowel/bladder (rare), and difficulty with balance or walking.

Spondylolysis and Spondylolisthesis

What can we do?

First, you can consult with your Doctor to obtain an MRI, CT, Bone scan, or X-ray to confirm the diagnosis and determine the extent of the injury. Treatments can involve both operative (surgical) or nonoperative/conservative management (Physical Therapy, NSAIDs/analgesics, and bracing). Generally, surgical interventions are reserved for those with significant symptoms or failure of conservative treatments.

With spondylosis, conservative management involving aerobic exercises such as biking and general strengthening and stretching of your whole body has been correlated to greater quality of life among adults with lumbar osteoarthritis 3. In addition, maintaining good posture throughout and maintaining our postural muscle strength can help to decrease pain and promote proper muscle length-tension relationships.

With spondylolysis, as with any fracture, your body will need time to heal. This means 4-8 weeks (or longer) of rest from high impact activities such as sports and lifting heavy items. Your Doctor may also recommend pain medications such as NSAIDs or steroids to help reduce pain and inflammation. During this time, Physical Therapy may be recommended and can help with facilitating the healing process, reduce pain, strengthen and stabilize specific muscles, and help you navigate through your everyday activities.

In addition, with both spondylolysis and spondylolisthesis, studies have shown that specific strengthening of the deep multifidus and transversus abdominis can be beneficial for spinal instability that commonly occurs 3,4. Overall, exercises to promote the full spinal range of motion and lumbar strengthening exercises have been proven to be a successful treatment option for decreasing pain and functional limitations 2,4,5. At PT First, our therapists have treated multiple patients with success when using this evidence-based method. If you have any questions, don’t hesitate to ask any of our licensed therapists!

References

Middleton, Kimberley, and David E. Fish. “Lumbar Spondylosis: Clinical Presentation and Treatment Approaches.” Current Reviews in Musculoskeletal Medicine 2, no. 2 (March 25, 2009): 94–104.

Garet M, Reiman MP, Mathers J, Sylvain J. Nonoperative treatment in lumbar spondylolysis and spondylolisthesis: a systematic review. Sports Health. 2013;5(3):225-232. doi:10.1177/1941738113480936

VIEIRA, S., et al, Abdominal muscle strength is related to quality of life among older adults with lumbar osteoarthritis. Journal of bodywork and movement therapies, 2015. (level of evidence 2A)

Kalichman L, Hunter DJ. Diagnosis and conservative management of degenerative lumbar spondylolisthesis. Eur Spine J. 2008;17(3):327-335. doi:10.1007/s00586-007-0543-3

Back Pain: Spondylosis, Spondylolysis, and Spondylolisthesis. SPARCC Sports Medicine – Tucson AZ. https://sparcctucson.com/2019/03/21/back-pain-spondylosis-spondylolysis-and-spondylolisthesis/. Published October 23, 2019. Accessed August 2, 2020.

Images:

https://www.braceability.com/blogs/articles/lumbar-spondylolisthesis-vs-spondylolysis
www.youtube.com/watch?v=3SoNJ5ELR6Y

The Acute Effect of Cryotherapy on Muscle Strength and Shoulder Proprioception

by Sarah Voelkel Feierstein PT, DPT, OCS, CMPT

Introduction

Cryotherapy is a common intervention used in clinical and athletic environments, especially for acute injuries. Common forms of cryotherapy include an ice pack, ice massage, and cold-water immersion. Cryotherapy is used to decrease injury-related pain, muscle spasms and swelling. However, the cooling effect of cryotherapy can harm neuromuscular function, including muscle strength and proprioception. Proprioception is an individual’s ability to sense joint position, movement, and force as a means to discriminate body movement. The authors in the study, The Acute Effect of Cryotherapy on Muscle Strength and Shoulder Proprioception, analyze how cryotherapy affects the maximal force production of the shoulder external and internal rotator muscles and shoulder proprioception.

Methods

A randomized double-blind controlled trial was performed on 48 healthy women. The participants were randomly assigned to either the experimental or control group. The experimental group had 15 minutes of cryotherapy in the form of a crushed ice pack applied to shoulder and the control group had a body-temperature sand bag applied to the shoulder. Maximal voluntary isometric contraction (MVIC), force sense, threshold to detect passive movement (TDPM) and joint position sense (JPS) of the shoulder rotator muscles were assessed immediately before and after the intervention.

Muscle Strength Assessment

The MVIC of the shoulder’s internal and external rotators was recorded both before and after cryotherapy treatment. A dynamometer was used to record three MVICs and the average was recorded.

Force Sense Assessment

The force-matching procedures for the internal and external shoulder rotators were conducted at 20% and 50% of the participant’s MVIC. For force sense testing, participants were positioned like the MVIC assessment and instructed to achieve the target force using visual feedback. They were then asked to perform the same contractions without visual feedback. The mean from three trials was used for analysis.

Joint Position Sense Assessment

The authors passively positioned the participants’ shoulder into position and maintained for five seconds so the participant could memorize the position. The participant then actively moved her shoulder into the same position. The participants were blindfolded and wearing headphones during this test. Each participant performed this test three times and the average score was recorded.

Threshold to Detect Passive Movement Assessment

The participants were placed in the same seated conditions used to test JPS. Each participant was asked to press the remote button upon sensing any movement or change relative to the initial shoulder position, which was engaged at random by the tester. Three trials from two starting positions were used, and the shoulder was moved into either the internal or external shoulder rotation.

Results

The cryotherapy reduced the skin temperature of the experimental group to 12.5 degrees Celcius compared to 33.5 degrees Celcius in the control group as measured by a skin thermometer.

MVIC: There was significant impairment in the force production of both the shoulder internal and external rotator muscles by approximately 10% of muscle strength in the experimental group.

Force Sense: There were no significant changes in both muscle groups at 20% and 50% of MVIC in the experimental group when compared to the control.

JPS: The error of JPS in external and internal rotation increased significantly in the experimental group post-cryotherapy application.

TDPM: Cryotherapy significantly diminished the participant’s ability to detect motion in the rotator muscles.

Conclusions and Physical Therapy First Implications

The results of this study demonstrate impairments of shoulder strength and proprioception following cryotherapy application.  These results suggest that application of an ice pack is harmful when it precipitates activity or exercise. There is a growing consensus that reduced shoulder proprioception increases the risk for sustaining a musculoskeletal injury. Athletes and trainers shoulder be educated on the proper timing of cryotherapy application for overhead athletes in order to decrease the risk for injuries. Cryotherapy is a modality we administer during rehabilitation which can help to reduce pain, swelling, and muscle spasm. At Physical Therapy First, we are conscious about the timing of cryotherapy intervention.

Reference:

Torres, R., Silva, F., Pedrosa, V., Ferreira, J., and Lopes, A. (2017). The Acute Effect of Cryotherapy on Muscle Strength and Shoulder Proprioception. Journal of Sport Rehabilitation. 26, 497 -506

Whole-body Cryotherapy as a Recovery Technique after Exercise: A Review of the Literature

by Sarah Voelkel Feierstein PT, DPT, OCS, CMPT

Introduction

In the days following unaccustomed or intense training or competition, athletes often experience dull, aching pain, stiffness, and loss of muscle strength that can last for up to 5-7 days. This phenomenon is termed exercise-induced muscle damage (EIMD). Muscle damage is characterized by a sustained reduction in optimal force production, the delayed onset of muscle soreness (DOMS), and an acute inflammatory response. It has been proposed that cold therapies aid recovery following EIMD through a dampening of the inflammatory response, edema reduction, and through an analgesic effect.

A novel form of cold therapy, Whole Body Cryotherapy (WBC) has gained popularity in athletes as an anti-inflammatory treatment. A typical session of WBC involves standing in a chamber that fills with a safe, but extremely cold gas, maintained at temperatures of -110 degrees Celsius to -190 degrees Celsius (-166 to -220 degrees Fahrenheit) for at least two minutes and a maximum of five minutes. The authors in the study, Whole-body Cryotherapy as a Recovery Technique after Exercise: A Review of the Literature, present an overview of the current research on the topic and provide recommendations for its use by athletes.

Discussion

Four key outcome measures for EIMD utilized in this review include pain, muscle function and performance, inflammatory marker levels, and creatine kinase (CK) levels as a marker of muscle damage.

Pain

The visual analog scale was utilized in the five articles that used pain as an outcome measure. Four studies found a significant decrease in pain by at least 18% when compared to a control at 48 hours post WBC treatment. In one study, there was also decreased pain compared to the control group when performing a body weight squat post-WBC treatment, suggesting WBC treatment may reduce pain during subsequent muscle contractions.

Muscle Function and Performance

Patients received an average of 15 WBC treatment exposures across the six studies that measured muscle function. In one study, a group of tennis players were exposed to WBC every day over a five-day training program. In this study, the WBC group reached fatigue significantly later during a progressively more difficult tennis drill than a control group. The WBC group also experienced a 7.3% increase in stroke effectiveness during a tennis skill game that became progressively more difficult where the control group only increased by 2.6%. In another study, synchronized swimmers were exposed to WBC each day during a period of intensified training and found that a 400 m time trial swim speed was only 0.5% slower after WBC compared to a 1.1% time reduction in the group that did not receive WBC treatment.

Inflammation

The authors who focused on inflammatory marker levels used concentrations of interleukins, tumor necrosis factor (TNF), and C-reactive protein (CRP) to show the amount of inflammation present in the muscle. One study looked at the inflammatory response in runners following a 48-minute simulated trail run. Concentrations of the acute inflammatory marker, CRP, were increased by 515% from baseline in the control group and 123% in a WBC group. The increase of inflammatory interleukin cells that naturally occurs after damaging exercise was limited when participants were exposed to WBC compared to the control.

In another study which observed the effects of WBC prior to exercise, the concentration of the pro-inflammatory interleukin increased more than six times in the control group compared to athletes who were treated with WBC. In addition, interleukin concentration dropped by 11%, indicating that treatment blunted the inflammatory response and possibly reduced muscle damage. Yet another study found WBC increased the concentration of an anti-inflammatory cytokine to twice that of baseline compared to no change relative to baseline in the control group. Further, the interleukin concentrations dropped by 80 % in the WBC group compared to a drop of only 50% in the control subjects . The final study found that a five-day training protocol combined with WBC induced a 60% decrease in the inflammatory cell, TNF-α.

Muscle Damage

Muscle damage focused studies used a measure of CK to determine the amount of breakdown in muscles. One study showed a 30% decline in CK after ten exposures to WBC over a five-day period as compared to a control group. A second study reported that CK concentrations were 34% lower with the inclusion of WBC treatment six days into a training protocol compared to a training protocol without WBC treatment. These results were supported by a separate study that reported daily exposure to WBC over a five-day training program with elite rugby players reduced CK by 40%. Another study found WBC treatment significantly reduced CK in tennis players where concentrations of this muscle enzyme in the control group remained virtually the same after five days of training. A final study found no significant changes in CK relative to a control group with protocols using either three or six exposures to WBC. The results from this study suggest that there may be a dose response to WBC when assessing CK concentration, where a reduction in circulating CK is in proportion to the number of exposures to WBC during the recovery process.

Limitations and Future Research

The lack of ability to blind for recovery treatment in the research makes it impossible to eliminate the potential placebo effect. Further investigation into the effects of multiple WBC exposures during extended periods of athletic training is warranted to determine potential effects on recovery, performance and processes of muscle adaptation. Future studies will require larger sample sizes to determine the significance of immunological changes and stringent methodological control to identify the exact influence of WBC on these pathways.

Conclusion

In conclusion, the studies referenced in this article suggest that WBC may be successful in decreasing pain, inflammation, and muscle damage and increasing muscle function. With WBC treatment groups recording pain scores an average of 31% lower than control groups, evidence tends to favor WBC as an analgesic treatment after damaging exercise. Data from inflammatory markers and CK suggest that WBC may dampen the inflammatory cytokine response which means less tissue damage and a faster recovery. Multiple exposures of three or more sessions of three minutes conducted immediately after and in the two to three days post-exercise have presented the most consistent results. There are contraindications to this modality including hypertension, circulatory disorder, and history of a stroke, to name a few. The athlete or patient needs to be properly screened and perform a thorough healthy history prior to treatment.

PT First Implications

As the research on WBC continues to evolve, this treatment could be a good adjunct to skilled physical therapy during an athlete’s training. Localized cryotherapy is a common modality seen in a physical therapy setting to treat pain and inflammation. WBC provides an avenue to treat more widespread muscle pain in multiple area of the body and could be beneficial for athletes during their training season.

Reference:

Rose, C., Edwards, K., Siegler, J., Graham, K., Caillaud, C (2017). Whole-body Cryotherapy as a Recovery Technique after Exercise: A Review of the Literature. International Journal of Sports Medicine. 38: 1049-1060.

Symptoms, Signs, and Functional Disability in Adult Spondylolisthesis

by Kayla Coad, PT, DPT

Introduction:

Spondylolisthesis is characterized by anterior slippage of a vertebrae. The purpose of this study is to determine if there are specific signs (what can be observed), symptoms (what is felt by the patient, eg pain), and functional disability that are associated with adult spondylolisthesis.

Methods:

Signs, symptoms, and disability of 111 patients with adult spondylolisthesis before randomized treatment with fusion or physical therapy were compared with those of 39 patients with nonspecific low back pain before lumbar fusion.

Results:

Symptoms were similar in patients with spondylolisthesis and chronic LBP, but chronic LBP reported greater functional disability. Patients with chronic LBP were on sick leave more often and reported a higher frequency of bladder and sexual dysfunction. Sixty-two percent of patients reported LBP as well as sciatica, 7% reported sciatica only, and 31% LBP only. Specific signs were not common. A positive straight leg raise test resulted in 12% and a L5 sensory distribution in 13% were the most common.

Conclusion:

The clinical presentation and functional disability is similar in patients with adult spondylolisthesis and low back pain of nonspecific origin. Patients with adult spondylolisthesis and sciatica do not typically have a positive straight leg raise test. Specific signs between the two groups were not common.

Clinical Relevance:

The physical therapist at Physical Therapist First will create a unique treatment plan based on research for patients with low back pain and adult spondylolisthesis in order to help them return to previous level of function. Reference: Moller, H., Sundin, A., Hedlund, R. Symptoms, Signs, and Functional Disability in Adult Spondylolisthesis: Spine. Vol 25, Number 6, pages 683-689.

Mechanisms of Acute Knee Injuries in Bouldering and Rock Climbing Athletes

by Sarah Voelkel Feierstein PT, DPT, OCS, CMPT

Mechanisms of Acute Knee Injuries in Bouldering and Rock Climbing Athletes


Introduction

The popularity of rope climbing and bouldering has increased significantly over the past few years and has recently been selected as a new discipline for the 2020 Summer Olympics. With the worldwide indoor bouldering boom comes an increase in injury numbers. In bouldering, the lower extremity tends to have more acute injuries unlike the upper extremity which are typically overtraining injuries. The authors in the study, Mechanisms of Acute Knee Injuries in Bouldering and Rock Climbing Athletes, analyze and describe various traumatic mechanisms of injury, patient demographics, and severity of acute knee injuries in noncompetitive and competitive athletes.

Methods

Between 2015 and 2018, noncompetitive and competitive athletes with acute knee injuries related to rope climbing or bouldering were evaluated at an outpatient sports medicine clinic specializing in rock climbing injuries. Diagnoses were made after a clinical examination by a senior orthopedic knee surgeon and radiographs. Athletes were asked to describe the exact mechanism of injury (MOI) which caused the injury and were assigned an experience level classification based on the Union Internationale des Associations d’Alpinisma (UIAA) metric scale. Patients were treated according to individualized protocols and gradually returned to their sport. All patients were seen for a follow-up evaluation at 6- and 12-weeks post-injury.

Results

Over the four-year period, 71 patients were treated with 77 independent acute knee injuries. Four types of traumatic MOIs were identified and are shown in the photo below: the high step position (A), the drop knee position (B), the heel hook position (C), and a fall to the ground (D). Almost half (48.6%) of all of the injuries happened during indoor bouldering, followed by outdoor rope climbing (26%), outdoor bouldering (22.1%), and indoor rope climbing (5.2%).

rock climbing injury

The most common diagnosis reported was a medial meniscus tear predominately caused by the high step, drop knee, and heel hook positions. Iliotibial band (ITB) sprains were the second most common diagnosis caused almost exclusively from the heel hook position. Anterior cruciate ligament (ACL) tears combined with medial collateral ligament (MCL) and medial meniscus injuries were detected in 9% of patients and isolated ACL tears in 2.6%. 91% of injuries that caused a partial ACL tear resulted from a fall to the ground. All athletes returned to rock climbing within twelve months.

Between-Group Comparison

High step and drop knee injuries were more common during rope climbing, whereas heel hook and fall injuries were more often caused by bouldering. Patients injured during the heel hook position had the highest ability level and highest training volume per week while patients injured during a fall had the lowest ability level. Competitive athletes were significantly younger and lighter than noncompetitive athletes. Medial meniscal tears and surgical intervention were more common in noncompetitive athletes.

Discussion

This is the first study to describe traumatic MOIs, injury patterns, and outcomes of acute knee injuries in rock climbing athletes. Injuries caused by bouldering activities account for almost 70% of all knee injuries sustained during climbing activities. One explanation is that bouldering routes normally consist of few but very hard moves which require strength and difficult body positioning, placing enormous stress on the medial knee.

ACL tears were more common in females and resulted from a fall. This pattern is similar to other sports were insufficient landing patterns with increased knee valgus is cause for an ACL injury. These ACL injuries were found in athletes with less experience and potentially less body control, stability and strength while landing. Many inexperienced athletes tend to choose indoor bouldering because of the ease of access. All of the athletes with ACL injuries had returned to the sport within one year. Unlike other sports which require running and jumping, the return to sport protocol for rock climbing is more gradual and relatively quick.

Medial meniscus injuries were predominately caused by the high step, drop knee, and heel hook positions. The peak load on the meniscus during these difficult positions is thought to be the cause of these injuries, in addition to insufficient technical skills and fatigue which might cause harmful rotation motion of the knee.

To prevent reinjury, rope climbing is preferred to bouldering to avoid falls and direct contact during the rehab process. The climber can also “down climb” (cautious decent) or “top out” (alternative easy decent) rather than jumping down. It may be possible to develop training programs for both competitive and noncompetitive athletes to address muscle weaknesses and landing patterns. Most climbers neglect the important leg muscles in their training. Active training of the knee stabilizers is important for improved joint control and stretching (ITB) may be advisable. Improved psychomotor skills and body control might better manage and reduce the risk of injury during falls.

Conclusion

There are four distinctive MOIs of knee injuries in rock climbers. Meniscal tears, ITB sprains, and ACL injuries are the leading injury diagnoses and the return to sport is relatively quick. Noncompetitive athletes have significantly more medial meniscus tears and undergo more surgical procedures than competitive athletes. ] Sport-specific awareness training programs to avoid excessive loads on the knee should be developed.

PTF Implications

With the increase in popularity and opening of indoor bouldering gyms near our clinics, our therapists are familiar with evaluating and treating climbing injuries. This study presents with data on acute knee injuries and important MOI data to assist in building preventative and rehabilitation programs. A skilled PT can help to assess knee loading during landing and screen for weakness and/or movement patterns in the lower extremities which could be concern for a knee injury. Our therapists are also highly trained in rehab protocols following an acute knee injury and aim to get patients back on the wall as quickly as possible.

Reference

Lutter, C., Tischer, T., Cooper, C., Franks, L., Hotfiel, T., Lenz, R., Schoffl, V. (2020). Mechanisms of Acute Knee Injuries in Bouldering and Rock Climbing Athletes. The American Journal of Sports Medicine. 48(3):730-738.