Weight gain during pregnancy leads to a multitude of anatomic changes that affect the lower limb. These biomechanical factors likely play a larger role in limb pain than do hormonal changes [1]. Increased lordosis of the low back and relaxation of the peripelvic muscles, primarily the hip abductors that are responsible for stability of the lower limb, can lead to a redistribution of forces through the knee and into the foot. Women become more flat-footed, leading to greater pronation [2] and alteration of pressure points throughout the plantar surface [3]. In combination with pregnancy-related pedal edema [4], ligamentous laxity in the foot and ankle also places more strain on soft tissues. The plantar fascia, a thick band of connective tissue running from the heel to the toes, often becomes stretched or inflamed, a condition known as plantar fasciitis. In the general population, plantar fasciitis is related to overuse or can be instigated by an injury, changes in activity patterns, or poor footwear, though the natural history of the disease is not understood [5]. Obesity is present in 70 % of nonpregnant individuals with heel pain [6], so in pregnant women who have gained weight, the altered kinetic chain and compression directly on the plantar fascia can lead to acute inflammation or chronic disorganization of the tissue, causing severe pain with weightbearing. The most common complaint is pain when taking the first couple of steps in the morning or after a period of inactivity [7], such as when getting up from a desk at work. The relative immobilization of the foot leads to tightening of the connective tissues, and only after moving around or stretching do they begin to loosen up.

When working up a gravid woman with foot pain, plain films are reserved to rule out a fracture from a traumatic event or if looking for degenerative changes, evidence of osteonecrosis, or dislocation. The majority of times, diagnosis based upon physical examination is sufficient. There is tenderness directly over the plantar fascia and pain is often reproduced in the heel with walking. Tenderness in the posterior heel along the insertion of the Achilles onto the calcaneus is more suggestive of Achilles tendinosis or enthesopathy than plantar fascial pain, though the two pathologies can coexist. Pinching the calcaneus between the thumb and index finger is important to help differentiate between plantar fasciitis and a calcaneal stress fracture. If the squeeze test is positive and the history is consistent with a possible bony abnormality, an MRI may be indicated to rule out the stress injury. Calcaneal stress fractures or reactions can be treated with a walking boot until pain abates. These are relatively uncommon, however, and in the vast majority of plantar heel pain, the fascia is the pain generator.

Managing foot pain during pregnancy is completely conservative. The mainstay of treatment is proper footwear, finding a comfortable walking shoe that gives support to the heel and to the arch. Full-length off-the-shelf inserts with a medial arch support may help correct pes planovalgus and realign the ankle, redistributing forces on the plantar surface of the foot, though there is no established evidence that they decrease pain [8]. Stretching of the foot in a dorsiflexed position, using a belt or band or towel, before getting out of bed in the morning alleviates pain with that first step, and manual and active stretching of the gastrocnemius and soleus is beneficial [9]. If the woman can tolerate exercise, structured physical therapy to learn hip stability and balance drills is also recommended. Treating the entire leg, not just the foot, can accelerate relief of symptoms and help prevent other musculoskeletal pain. Massage to the foot, to the calf, and into the thigh and hip, foot ice baths, elevation, relative rest, night splinting, and rolling a ball or frozen water bottle on the bottom of the foot are other methods of treatment that have some success. In the extreme cases, a walking boot for 7–14 days may help with acute pain. It is important to direct the patient to remove the boot periodically throughout the day, as stiffness in the ankle and atrophy of the calf from long-term disuse can lead to unintended pain and weakness. Corticosteroid injections have been shown to give short-term relief of plantar fascial symptoms up to 6 months [10], so while these injections do not fix the problem, they may be necessary to keep women active and on their feet.

A common question during pregnancy is about the safety of over-the-counter pain medications. Nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen and naproxen, may pose danger to the fetus [11], particularly during the third trimester. For this reason, the Federal Drug Administration has categorized all NSAIDs as Class D after 24 weeks, meaning that there is some evidence of NSAIDs causing human fetal risk [12]. They should only be used in the case of life-threatening illness or when the use of safer drugs is ineffective or not an option. In contrast, acetaminophen (Tylenol) has not been associated with significant fetal risk and is categorized as Class B during all three trimesters [13]. This designation means that there are no good randomized controlled trials in human subjects and that no adverse effects have been found in animal reproduction models. Though there has been some correlation made between acetaminophen use in pregnant women and increased incidence of ADHD in 7- to 11-year-olds [14], acetaminophen has been widely accepted as the pain medication of choice and should be the initial pharmacotherapy if needed during pregnancy.

Patellofemoral pain (PFP) is the most common running injury, accounting for between 25 and 40 % of all knee pain [15]. The classic teaching is that it is caused by maltracking of the patella in its femoral groove during repeated flexion of the knee. The lateral quadriceps is thought to overpower the medial quadriceps, pulling the patella laterally. Often the articular cartilage on the undersurface of the kneecap can wear away, a related disorder called chondromalacia patella, which is often used interchangeably with PFP and runner’s knee but that means something a bit different in terms of pathology. There is some evidence that patellofemoral arthritic changes contribute significantly to PFP, primarily in the setting of patella alta [16]. The most common symptoms of patellofemoral pain syndrome or “runner’s knee” are generalized anterior knee pain with running, difficulty going down stairs, and stiffness with the knee flexed for an extended period, described usually as pain when getting up from a seated position [17].

Though quadriceps weakness does likely play a role in PFP, quadriceps tightness is often more prevalent in patients with anterior knee pain. Knee restriction places more pressure on the patella, causing stiffness after a period of immobility. Trigger points in the quadriceps can also decrease joint range of motion and refer pain to the knee joint, despite the knee itself having no structural problem. Treatment for PFP thus begins with regaining or maintaining knee flexion when compared to the asymptomatic side. Active quadriceps stretching, soft tissue mobilization with a foam roller or PVC pipe, manual tissue work with a therapist or chiropractor, and dry needling to release active trigger points are all initial strategies to regain this motion.

The knee is like a middle child: it takes all the abuse from the older sibling, the hip, and the younger sibling, the foot and ankle. The gluteal musculature, particularly the gluteus medius, is critical in stabilizing the lower limb during single-leg stance and ambulation, which is essentially a series of repetitive single-leg activities. The foot and ankle, meanwhile, control alignment of the tibia and subsequently the entire leg and thigh. Weak gluteus medius can lead to a loss of stability and alter pelvic mechanics [18], and a weak or flat foot can lead to a loss of proper alignment, both placing more stress on the knee and leading to anterior joint pain. Women with PFP have been shown to have greater more pelvic drop [19], indicative of weak gluteals, and more hip adduction [20], which may correlate mechanically to weak abduction. Rehabilitation of PFP focuses on correction of biomechanical abnormalities, beginning with the hip, foot, and ankle. Hip abductor and core stability, balance, foot intrinsic strengthening, correction of any dorsiflexion or plantar flexion contracture, and proprioceptive training are mainstays of a therapy program, with some evidence that hip plus knee exercise is better than knee exercise alone [21]. Those with pes planovalgus or rearfoot eversion may benefit from off-the-shelf orthotics with a medial arch support to help control tibial alignment, as there may be a link between tibal rotation and PFP [22].

Patellofemoral pain is more common in women than men [23], because of factors that affect the general population and because of anatomic changes that occur naturally from pregnancy itself. Additional weight puts more stress on the joints; hormonal changes lead to ligamentous laxity and subsequent weakness, especially in the hips and pelvis; and postural changes caused by the gravid uterus can alter gait mechanics [24].

One of the most common questions that runners and other active women have during pregnancy is whether or not they can continue to exercise. While there are no specific guidelines on what women can or cannot do while pregnant, it is widely accepted that they should follow the same recommendations as for nonpregnant women and men: 30 min of moderate-intensity exercise at least 5 days a week [25]. The American Congress of Obstetricians and Gynecologists (ACOG) recommend that in uncomplicated pregnancies, recreational and competitive athletes maintain their level of exercise and modify as medically indicated [26]. This differs from ACOG’s recommendation for sedentary women, who instead require a full medical evaluation before beginning an aerobic training program.

Evaluation of a runner with knee pain begins with analysis of walking gait and then with the patient standing barefoot on a single leg, looking for proper balance, signs of hip weakness, and low or high arches of the feet. It is important to check range of motion and strength of the hip, knee, and ankle, paying close attention to any differences between the symptomatic and asymptomatic sides. Palpate the knee for an effusion, which would suggest intra-articular damage, and look for tenderness along the medial and lateral joint lines, patellar and quad tendons, and popliteal fossa. Special tests are used to help rule out ligament sprains or meniscal and articular cartilage injury. Palpation of soft tissues may reveal taut bands and trigger points that can refer pain to the knee and contribute to symptoms.

In the absence of trauma, infection, effusion, mechanical symptoms such as locking, instability or feelings of giving way, suspected arthritis or fracture, or intractable pain, there is no need for plain films or advanced imaging.

Weight gain and stretching of the abdominal cavity by the gravid uterus increase lumbar lordosis and lumbosacral stiffness, weaken core musculature, exaggerate hip flexion, protract the cervical spine, and depress the shoulder blades, all placing more strain on the lumbar paraspinal muscles, particularly during weightbearing. Interestingly, though gait mechanics have been shown to change very little in pregnancy, the hip extensors, hip abductors, and foot plantar flexors are all more active during ambulation to compensate for anterior pelvic tilt [27]. These changes, in combination with the well-established hyperlaxity of the sacroiliac joints and pubic symphysis, all place a pregnant woman at greater risk for back pain. Additional risk factors include pain before pregnancy, back pain during a previous pregnancy [28], and multiparity, though the biggest risk factor is the progression of pregnancy [29].

The majority of back pain, both in the general population and among pregnant women, is axial [28] and mechanical in nature, that is, related to movement. Causes include poor posture, muscle weakness, irritation of the joints in the lumbar spine and pelvis, ligamentous laxity, and a host of other biomechanical factors, including gait abnormalities and prior injuries leading to compensation. Rarely is an anatomic cause found, meaning that back pain can most often be treated according to the resulting dysfunction and constellation of symptoms rather than based upon a specific pathology. While pregnant women are at risk for spondylolisthesis, slippage of one vertebrae over another, there is no greater prevalence of disc herniation in this population [30]. The history and physical examination are thus used to rule out the uncommon pathology, such as symptomatic disc herniation, and to determine modifiable risk factors, extent of functional loss, and anatomic asymmetry and weakness, all with the goal of developing an individualized treatment plan.