10.1 Acquired and Congenital Musculoskeletal Conditions

10.1 Acquired and Congenital Musculoskeletal Conditions

Quick Answer: Preterm metabolic bone disease presents with rising alkaline phosphatase and low phosphorus—not a low calcium—and it predisposes to occult rib and long-bone fractures. Separate birth fractures and brachial plexus injury from infection of bone and joint, and treat a septic hip as a limb-threatening emergency. Congenital problems range from cleft and limb-reduction defects to osteogenesis imperfecta and developmental dysplasia of the hip; open neural-tube skeletal findings overlap the surgical nursing in the next section.

Why these problems sit on the Neonatal CCRN Test Plan

The current Neonatal CCRN Test Plan lists acquired musculoskeletal conditions and congenital musculoskeletal conditions as separate patient problems. OpenExamPrep teaches them in one section because the nurse uses the same hands for both: a gentle lift, a symmetric motor exam, and a high index of suspicion when a preterm infant suddenly will not move an arm. Independent practice items for this credential are at /practice/ccrn-neonatal. Pediatric CCRN bone and spine teaching is organized separately at /study-guides/ccrn-pediatric; adult CCRN musculoskeletal content lives at /study-guides/ccrn.

Intracranial hemorrhage, hypoxic-ischemic injury, and pain or state dysregulation are not the job of this chapter. Those neurologic injury topics continue in the next study-guide chapter. Birth trauma that is not primarily a bone, joint, or plexus problem—subgaleal hemorrhage, extra-cranial collections, hydrops—belongs with the later perinatal multisystem chapter. Teach the clavicle, the plexus, and the osteopenic rib here.

Osteopenia of prematurity

Most fetal calcium and phosphorus accretion happens in the third trimester. Near term, calcium transfer is often cited near 120–150 mg/kg/day and phosphorus near 70 mg/kg/day. An infant born at 24–28 weeks misses weeks of that transfer. Parenteral nutrition that cannot match in-utero mineral delivery, delayed fortified enteral feeds, fluid restriction, cholestasis, immobilization in a ventilator circuit, and drugs that waste mineral—loop diuretics and glucocorticoids are the usual pair—widen the gap. The result is osteopenia of prematurity, also called metabolic bone disease of prematurity: reduced bone mineral with or without radiographic rickets.

The clinical picture is quiet. You may notice a rachitic rosary, craniotabes, or an unexplained fracture on a chest film obtained for a wean. Peak laboratory disturbance is commonly between 4 and 12 weeks of age, not on the first postnatal day. Term-corrected age is a high-risk window for an occult fracture even with ordinary cares.

Screening is biochemical first. Serum calcium is frequently normal until late, which is the classic exam trap. Phosphorus falls. Parathyroid hormone may rise as the infant defends calcium at the expense of bone. Alkaline phosphatase (ALP) climbs with bone turnover. Many teams treat a rising ALP above about 500–800 IU/L as a prompt to review mineral intake, especially when phosphorus stays below about 4.5–5.6 mg/dL (about 1.5–1.8 mmol/L). No single ALP number diagnoses rickets. ALP can be misleadingly lower with zinc deficiency or steroid exposure, and it can rise with fracture healing or cholestasis, so pair it with phosphorus, a nutrition review, and sometimes PTH and 25-hydroxyvitamin D. Radiographs lag: a large fraction of mineral must be lost before osteopenia is obvious. Wrist or knee films enter the plan when biochemistry stays abnormal on serial checks.

Prevention is the intervention that actually cuts fractures. Maximize calcium and phosphorus in parenteral nutrition once fluid volume allows, advance fortified human milk or preterm formula, provide vitamin D per unit protocol, and stop loop diuretics when the lung allows. Handle-with-care programs—two-person cares, no chest percussion in a demineralized infant, caution with blood-pressure cuffs and heel sticks—sit beside nutrition, not instead of it. Quality-improvement bundles that combine mineral targets with gentle handling have dropped NICU fracture rates in extremely preterm cohorts from the high single digits into the low single digits.

Fractures: birth injury versus fragile bone

Clavicle fracture is the most common birth fracture. You may feel crepitus, see an asymmetric Moro reflex, or notice a lump after a few days of callus. The humerus and femur fracture less often and raise questions about extraction trauma, breech maneuver, or later osteopenia. Rib fractures in a six-week-old extremely low-birth-weight infant on furosemide are osteopenia until proven otherwise. They are not automatically maltreatment. Unexplained fractures in a well term infant still require a careful differential that includes osteogenesis imperfecta and, when the history does not fit, a child-protection pathway taught with behavioral content later in this guide.

Nursing care is practical. Immobilize as directed—often a soft wrap or pinning the sleeve for clavicle or humerus—treat pain, teach parents that callus is expected, and document which limb was affected and when movement returned. For osteopenic fractures, fix the mineral problem and keep handling gentle. Orthopedic pinning is uncommon unless displacement threatens vessels or a growth plate.

Worked scenario. A 25-week infant, now 7 weeks old, remains on furosemide for evolving chronic lung disease. A chest radiograph for a respiratory wean shows two posterior rib fractures. ALP is 920 IU/L and phosphorus is 3.8 mg/dL. Calcium is 9.1 mg/dL. The first moves are analgesia, handle-with-care, and a mineral, PTH, and vitamin D review—not a lumbar puncture and not an assumption of inflicted injury as the leading story in this gestational-age and medication context.

Brachial plexus: Erb versus Klumpke

Neonatal brachial plexus palsy follows traction on the neck or arm, especially with shoulder dystocia, macrosomia, or breech. Incidence is on the order of 0.5–2 per 1,000 live births. Erb-Duchenne palsy (C5–C6, sometimes C7) is the common pattern: shoulder adducted and internally rotated, elbow extended, forearm pronated, wrist flexed—the waiter's-tip posture. Grasp is often preserved because C8–T1 still supply the hand. The Moro is asymmetric. The biceps reflex is weak.

Klumpke palsy (C8–T1) is uncommon in isolation. The hand is clawed, intrinsic muscles and finger flexors fail, and grasp is lost. Involvement of sympathetic fibers at T1 can add Horner syndrome—ptosis, miosis, and anhidrosis—on the same side. Total plexus palsy presents as a flail, insensate arm and has a worse motor prognosis.

Immediate care is protection, not aggressive range on a numb shoulder that may also hide a clavicle or humeral fracture. Exclude fracture, then prevent contracture with gentle passive motion, avoid hanging the arm off the mattress, and watch for diaphragmatic weakness if upper roots are involved (asymmetric chest excursion, unexplained tachypnea). Most Erb palsies improve over weeks to a few months. Lack of biceps recovery by about 3 months is a typical trigger for specialty referral and possible imaging. Do not promise families that the arm always comes back. Document a complete baseline exam on admission so later change is visible.

Osteomyelitis and septic arthritis

Neonatal bone and joint infection is usually hematogenous. Staphylococcus aureus, group B Streptococcus, and gram-negative enteric organisms dominate. Candida appears in the extremely preterm infant with central lines. Multiple bones can be involved in the same infant. The bedside picture may be fever or temperature instability, irritability with handling, pseudoparalysis (refusal to move a limb), local swelling, or a septic picture without a dramatic red joint.

Septic arthritis of the hip is an emergency. The neonatal femoral head has a tenuous blood supply; pus under pressure can produce avascular necrosis within hours to days. Ultrasound looks for effusion. MRI or bone scan is used when osteomyelitis is suspected and plain films are still normal—they often are in the first days. Blood culture, C-reactive protein, and a complete blood count inform the workup but do not replace source control. Intravenous antibiotics start after cultures when the infant is stable enough to obtain them; the hip still needs urgent orthopedic drainage if effusion is confirmed. Do not treat “cellulitis of the groin” with observation in a neonate who will not move the hip.

Long-bone osteomyelitis is treated with a prolonged IV-to-oral course directed by culture and imaging; the nurse’s job is immobilization for pain, vascular access that does not sit in an infected field, and serial neurovascular checks of the limb.

Craniofacial preview: cleft and Pierre Robin

Cleft lip and/or palate impair suction, increase nasal regurgitation, and raise later otitis and speech risk. Nursing priorities in the NICU are airway—especially if the tongue falls back—paced feeding with a specialized nipple or obturator as directed, upright positioning after feeds, and family teaching that this is a structural feeding problem, not a failure to “try harder.” Associated anomalies (heart, 22q11 deletion, Stickler syndrome) belong on the admission checklist.

Pierre Robin sequence—micrognathia, glossoptosis, and often a U-shaped cleft palate—is taught in full with other sequences in a later multisystem chapter. The preview you need now is musculoskeletal and airway, not a feeding slogan. The small jaw lets the tongue obstruct. Prone positioning, a nasopharyngeal airway, or surgical tongue-lip adhesion or mandibular distraction may be required. Do not force routine supine sleep teaching until the airway plan is explicit. This is one of the few NICU settings in which prone positioning is used for obstruction, not for an open neural-tube sac.

Limb-reduction defects and spine overlap

Limb-reduction defects include amelia, meromelia, and constriction-ring (amniotic-band) patterns. Historical teratogens such as thalidomide are teaching history. Today you look for vascular disruption, twin-related injury, and syndromic clusters. A missing radius prompts a VACTERL and cardiac look. A missing thumb changes the genetic conversation. Nursing is practical: protect residual limbs, adapt intravenous sites, involve occupational therapy early, and support parents who are grieving an unexpected limb difference.

Spine findings overlap congenital neurology. A simple sacral dimple that is midline, near the anus, and without a tuft or hemangioma is usually innocent. A high dimple, hairy patch, hemangioma, or subcutaneous mass raises concern for occult dysraphism and needs imaging. Meningocele (meninges only) and myelomeningocele (neural tissue in the sac) are neural-tube defects; the latex-focused and prone-dressing nursing is in the next section. Congenital scoliosis, hemivertebrae, and sacral agenesis travel with caudal regression and maternal diabetes—examine the lower limbs and the bladder, not only the curve.

Osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a type I collagen disorder, most often COL1A1 or COL1A2. Perinatal lethal type II presents with crumpled ribs, multiple intrauterine fractures, and an undermineralized skull. Survivors may have blue sclerae, hearing risk, wormian bones, and recurrent fractures with trivial handling. Distinguish OI from osteopenia of prematurity by gestational age, mineral pattern, and extra-skeletal signs. Distinguish both from inflicted injury by history, sclerae, dentinogenesis, and radiographic pattern (including healing fractures of different ages that still need a careful social review). Handle like glass: lift with a broad hand behind the back and buttocks; never pull by the ankles for a diaper change.

Developmental dysplasia of the hip, conceptually

Developmental dysplasia of the hip (DDH) is a spectrum from a shallow acetabulum to a dislocated femoral head. Risk flags are breech presentation, female sex, family history, and oligohydramnios. Barlow stresses a reducible hip out of the acetabulum. Ortolani reduces a dislocated hip back in with a clunk. Galeazzi (unequal knee height) and limited abduction appear later. In the NICU you perform a gentle exam, avoid tight extended-adducted swaddling, and arrange ultrasound when risk or exam is abnormal on the local timeline. Pavlik harness care is usually a post-discharge orthopedic skill. Know that a harness holds flexion and abduction and that skin checks under the straps matter.

Putting the musculoskeletal exam together

Every admission exam should include clavicles, symmetric spontaneous movement, Moro, grasp, hip stability, palate, and a look at the back. Re-examine after a traumatic delivery and again when a 6-week-old preterm infant has a rising ALP. Document what you can and cannot feel. Families need concrete teaching: how to lift an osteopenic infant, how to protect an Erb arm, how to feed a cleft, and when to call for a limb that suddenly looks swollen.

• Lift osteopenic and OI infants with a full-hand scoop, never by the ankles.
• Re-check movement after every traumatic delivery and after every new “won’t move this arm” report.
• Treat a septic-appearing hip as time-critical, not as a next-day orthopedic courtesy consult.
• Preview Pierre Robin as airway first; save the full sequence bundle for the later multisystem chapter.