Slipped Capital Femoral Epiphysis (SCFE)

residency days

1. Slipped C apital F emoral E piphysis Dr Sijan Bhattachan 2nd year resident , Orthopedic & Trauma Surgery Civil Hospital, NAMS

2. Introduction Disorder of proximal femoral physis that leads to slippage of metaphysis anteriorly and superiorly relative to epiphysis, which remains anatomically positioned in the acetabulum. Most common disorder affecting adolescent hips (about 10 per 100000) Children going through pubertal growth spurt. Boys ( 14-16 yrs ) are affected Left hip ; B/L in approx 25%.

3. Aetiology Slip occurs through hypertrophic zone of cartilaginous growth plate Most of patients are either fat and sexually immature or excessively tall and thin Hormonal imbalance Normally pituitary hormone activity, which stimulates rapid growth and increased physeal hypertrophy during puberty is balanced by increasing gonadal hormone activity, which promotes physeal, maturation and epiphyseal fusion. Disparity between these two processes may result in the physis being unable to resist the shearing stresses imposed by the increase in body weight

4. Perichondrial ring (the retaining collar around the physis) is relatively thinned in this age group and provides less support for the increased load transmitted through the physis during the growth spurt Trauma plays a part, especially in the 30% of the cases with an acute slip

5. Pathology In slipped epiphysis, femoral shaft rolls into external rotation and the femoral neck is displaced forwards while the epiphysis remains seated in the acetabulum. Epiphysis slips posteriorly on the femoral neck. Periosteum is stripped from anterior and inferior surface of femoral neck. If slip is severe, the anterior reticular vessels are torn At the back of femoral neck, the periosteum is lifted from the bone with the vessels intact; this may be the main or the only source of blood supply to femoral head and damage to these vessels by manipulation or operation may result in avascular necrosis

6. Area between femoral neck and posterior periosteum fills with callus which ossifies and becomes progressively dense. Anterior and superior portion of the neck forms a hump or ridge that can impinge on the rim of acetabulum. Normally, this ridge will remodel with anterior portion of neck contouring into smoother surface

7. Similar to Salter Harris type 1 fracture, but may differ by -antecedent epiphysiolysis. -slower displacement -periosteum remains intact (chronic SCFE); In acute cases. periosteum can be partially torn anteriorly over the prominent metaphysis

8. Associated conditions Endocrine disorders -Hypothyroidism -Renal osteodystrophy -Growth hormone deficiency -Panhypopituitarism Down syndrome

9. Presentation Symptoms Groin and thigh pain Limping Knee pain (15-50%; can lead to misdiagnosis) Symptoms are usually present for weeks to several months before diagnosis is made.

10. Physical examination Abnormal gait; Antalgic, waddling, Trendelenburg gait Decreased hip motion; Loss of hip internal rotation, abduction and flexion; Obligatory external rotation during passive flexion of hip ( Drehmann sign) Abnormal leg alignment; externally rotated foot progression angle Thigh atrophy

11. D/d Perthes disease Fracture of proximal femur Septic arthritis/ Osteomyelitis Adductor muscle strain Stress fracture

12. Imaging XRay AP view; epiphyseal plate seems to be too wide and too woolly; Ephiphyseolysis. A line drawn along the superior surface of the femoral neck should normally intersect the epiphysis. In the early slip, the epiphysis may be flush with or even below this line ( TRETHOWAN’s sign)/ Klein’s line

13. Blurring of proximal femoral metaphysis.( Metaphyseal blanch sign of Steel ); seen on AP due to overlapping of the metaphysis and posteriorly displaced epiphysis.

14. Capener’s sign;In normal hip, the posterior acetabular margin cuts across the medial corner of the upper femoral metaphysis. With slipping, the entire metaphysis is lateral to the posterior acetabular margin

15. In lateral view, the femoral epiphysis is tilted backwards. Minor abnormalities can be detected by measuring the angle subtended by the epiphyseal base and the femoral neck; this is normally a right angle; anything less than 87 degree means that the epiphysis is tilted posteriorly

16. Decreased epiphyseal height, physeal widening, lesser trochanter prominence due to increased external rotation of femur and new bone formation in the posterior femoral metaphysis, with anterior remodelling, are also useful signs in diagnosis

17. USG may detect a hip effusion associated with an acute event and may also show metaphyseal remodelling in a chronic slip MRI has been used -To diagnose preslip condition when radiographs are negative -To detect and stage AVN of femoral head

18. CT useful in preoperative planning of realignment procedures for complex proximal femoral deformities

19. Grading Based on timing of onset (Temporal classification) Preslip ; Groin or knee pain, particularly on exertion ; Limp Examination is often normal, but may demonstrate reduced internal rotation. XRay may show widening or irregularity of physis

20. Acute slip Symptoms present for less than 3 weeks Painful hip movements with an external rotation deformity, shortening and marked limitation of rotation

21. Chronic slip Symptoms lasting for more than 3 weeks Episodes of deterioration and remission Loss of internal rotation, abduction and flexion of hip Limb shortening

22. Acute on chronic slip Long prodromal history and an acute, severe exacerbation. This classification does not corelate to the risk of avascular necrosis or predict the outcome in the longer term

23. Loder et al (1993) ; Based on ability to bear weight. Stable; Child can walk with or without crutches; Minimal risk of AVN (<10%) Unstable; Walking not possible; 47% risk of AVN Provides prognostic information.

24. Radiological grading based on measurement of magnitude of slip relative to width of femoral neck or the angle of arc of slip On frog lateral xray, Mild; Displacement is less than one third of the width of femoral neck Moderate; Displacement is between one third and a half Severe; Displacement is greater than half of the femoral neck width

25. Southwick Slip angle classification ; Based on femoral epiphyseal-diaphyseal angle difference between affected and unaffected hip (On both AP and frog lateral pelvis radiograph; Mild; <30 degree Moderate; 30-50 degree Severe; >50 degree

26. Kullio et al classified based on USG findings. -Acute; Effusion without metaphyseal remodelling -Chronic; No effusion with metaphyseal remodelling.

27. Treatment Aims of treatment; To preserve the epiphyseal blood supply To stabilize the physis To correct any residual deformity. Manipulative reduction of slip carries a high risk of avascular necrosis and should be avoided.

28. Operative modalities Percutaneous insitu fixation Contralateral hip prophylactic fixation (B/L insitu fixation) Open epiphyseal reduction and fixation Osteochondroplasty Proximal femoral osteotomy

29. The choice of treatment depends on the degree of slip Minor slip; Deformity is minimal and needs no correction Position is accepted and the physis is stabilised by inserting one or two screws or threaded pins along the femoral neck and into the epiphysis, under fluoroscopic control

30. Moderate slip Deformity, though noticeable, is often tempered by gradual bone modelling and may in the end cause little disability. One can therefore accept the position, fix the epiphysis insitu and then wait. If after a year or two, there is a noticeable deformity, a corrective osteotomy is performed below the femoral neck

31. Severe slip Causes marked deformity which untreated, will predispose to secondary OA. Closed reduction by manipulation is dangerous and should not be attempted. Open reduction by Dunn’s method gives good results but should be reserved for specialist

32. Alternative method recommended for less experienced surgeon- is to fix the epiphysis as for a moderate slip and then, as soon as the fusion is complete, to perform a compensatory intertrochanteric osteotomy. Easiest is Triplane osteotomy with simultaneous repositioning of the proximal femur in valgus, flexion and medial rotation

33. Percutaneous insitu fixation Goal; To stablize the epiphysis from further slippage and promote closure of the proximal femoral physis. Technique; Single cannulated screw is sufficient and decreases risk of osteonecrosis (compared to multiple pins).; starting position being anterior of femoral neck and not lateral cortex. Screw should be perpendicular to physis, and enter into the central portion of femoral head on both AP and lateral views (center-center). Advance until 5 threads cross physis; should be at least 5 mm from subchondral bone in all views

34. One versus two cannulated screws is controversial 2 screws constructs have greater bimechanical stability than a single screw construct. Benefit of 2 screws needs to be considered in the face of greater risk of screw related complications

35. Postoperative; Stable slips are able to bear weight after fixation Unstable slips are kept touch down weight bearing for 6 weeks Outcome; Does not treat deformity at head neck junction Unsatisfactory outcomes in 10-20 % have resulted in advocacy of other techniques to correct the deformity and mitigate long term risk of chondral damage

36. Osteotomy in SCFE Because moderately or severely displaced chronic slips produce permanent irregularities in the femoral head and acetabulum, some form of realignment procedure often is indicated to restore the normal relationship of femoral head and neck and possibly delay the onset of degenerative joint disease. Two basic types of osteotomies - Closing wedge osteotomy through the femoral neck, usually near the physis to correct the deformity. - Compensatory osteotomy through the trochanteric region to produce a deformity in the opposite direction

37. Closing wedge osteotomy (femoral neck) Subcapital cuneiform osteotomy ( FISH / Dunn ) Base of neck osteotomy ( Kramer / Barmada ) Compensatory osteotomy (Trochanter) Imhauser osteotomy Southwick osteotomy

38. The nearer to the physis, the greater power of correction but with higher risks of AVN

39. Dunn procedure Trapezoidal osteotomy of the femoral neck Referred as “ an open replacement of the displaced femoral head” Should not be done if the physis is closed. Reduce capital femoral epiphysis on the femoral neck by resecting a portion of the superior femoral neck Advantage; the deformity itself is corrected High risk of AVN and chondrolysis.

40. Dunn osteotomy for severe chronic slips in children with open physics is based on two well known facts; -Slip of femoral head strips the periosteum from the back of femoral neck and a beak of new bone is laid down beneath it -the main reticular blood supply runs up the back of the femoral neck. A lateral approach allows stripping of periosteum and its contained vessels under direct vision to avoid damaging the blood supply to femoral head.

41. Greater trochanter is elevated and the femoral neck exposed. By gentle subperiosteal dissection, the posterior retinacular vessels are preserved while mobilising the epiphysis. A small segment of femoral neck is then removed, so that the epiphysis can be repositioned without tension on the posterior structures Once reduced, it is held by two or three pins.

42. Modified Dunn Procedure Surgical hip dislocation, Open capital realignment and fixation Goal; To correct the acute proximal femoral deformity, protect femoral head blood supply and stabilise the epiphysis. Technique Surgical hip dislocation via Gibson approach (Between Gluteus maximus and medius) Develop retinacular soft tissue flaps (anteriorly and posteriorly) Mobilize epiphysis (remains attached to posterior reticular flap)

43. Debride metaphysis (Prominent reactive callus along the posterior metaphysis, needs to be removed to permit proper epiphyseal reduction and avoid kinking of reticular vessels) Reduce epiphysis to metaphysis Fixation with 2-3, 3.0 mm K wires Postoperative; Touch down weight bearing for 6 weeks Complication rate of 37%

44. Base of Neck Osteotomy Indicated to correct residual deformity after closure of physis. Corrects varus and retroversion components of moderate or severe chronic SCFE. Pose less risk to interruption of blood supply to femoral head in comparision to Dunn procedure Osteotomy is held with threaded steinmann pins, which extends into the capital epiphysis if the physics is still open.

45. Kramer et al described an extra capsular basal neck osteotomy in an attempt to decrease risk of AVN. AVN and chondrolysis have still been reported.

46. Intetrochanteric osteotomy Southwick described an osteotomy at the level of lesser trochanter which corrects varus and extension deformity with no derotation to avoid abductor weakness. Biplane wedge osteotomy. Indicated for chronic or healed slips with head shaft deformities between 30 and 70 degrees

47. Imhauser osteotomy Goal; To correct symptomatic proximal femoral deformity in moderate to severe chronic SCFE deformity. Technique Lateral approach Transverse osteotomy just proximal to lesser trochanter Correction; -flexion through osteotomy -internal rotation of distal shaft -Mild valgus correction

48. Imhauser osteotomy It primarily corrects posterior angulation with secondary correction of external rotation and varus

49. Osteochondroplasty Goal; To address pain and loss of motion related to hip impingement from prominent metaphyseal bump in mild to moderate chronic SCFE deformity. Indications; -symptomatic femoroacetabular impingement (FAI) of true cam lesion from metaphysical bump -Mild to moderate SCFE deformity (slip angle<30 degree) Technique -Arthroscopy; Remove metaphyseal bump with arthroscopic burr -Limited anterior arthrotomy (Modified Smith Peterson approach) -Surgical hip dislocation

50. Complications Slipping at the opposite hip; In 20% of cases Asymptomatic hip should be checked by xray and at the least sign of abnormality, the epiphysis should be pinned. Risk factors; Male, obesity, young age of initial slip (<10 yrs;open triradiate cartilage), endocrine disorders Posterior sloping angle of more than 12 degree has been described as a predictive of development of contralateral slip. Weight loss programs.

51. Avascular necrosis; (4-6%) Mostly Iatrogenic ; Operative complication (Hardware placement in posteriosuperior femoral neck;disruption of vascular supply) May occur as result of initial trauma (Unstable slips) Minimized by avoiding forceful manipulation and operations which might damage the posterior retinacular vessels

52. Tamponade effect due to acute hemorhhage within capsule has been suggested as a cause of osteonecrosis but no evidence has indicated that immediate aspiration of hip joint is effective in preventing osteonecrosis. If a significant effusion is suspected, USG can be done to determine amount of effusiion and necessity of capsulotomy. If immediate (within 24 hours) stabilisation of an acute slip cannot be accomplished because of delayed presentation, a delay of at least 7 days has been recommended to avoid the “unsafe window” during which surgical intervention may increase the risk of osteonecrosis.

53. Physeal separation defined as the amount of separation of anterior lip of epiphysis from the metaphysis on a frog leg lateral radiograph. “Anterior physeal separation is associated with high incidence of subsequent osteonecrosis after SCFE” -Ballard and Cosgrove.

54. Articular chondrolysis; (0-2%) Probably results from vascular damage (often iatrogenic) . Associated with unrecognised implant penetration of articular surface Progressive narrowing of the joint space and the hip becomes stiff. Symptoms develop between 6 weeks and 4 months after treatment

55. Clinical features Stiffness Pain in groin or upper thigh Walking affected Hip held in flexion, abduction and external rotation Substantial reduction in the arc of motion of hip in all planes and motion is usually painful

56. Radiographically, Loss of joint space; Either loss of more than 50% of the joint space or an absolute measurement of 3 mmm or less (Normal is 4-6 mm) A technetium bone scan shows increased uptake in an affected joint space. CT of hip to confirm that no implant encroachment is present If pin penetration has occurred, the implant must be removed or replaced if the physis is not fused.

57. In some cases , condition improves spontaneously or with conservative management while in others it leads to loss of mobility and OA. If severe joint space narrowing persists with limitation of joint motion, arthrodesis or arthroplasty should be considered

58. Coxa vara; Result of unnoticed or inadequately treated Slipped epiphysis. Except in most severe cases, this is more apparent than real; the head slips backwards rather than downwards and the deformity is essentially one of femoral neck retroversion Secondary effects are external rotation deformity of the hip, possibly shortening of the femur and secondary OA Treatment is proximal femoral osteotomy (Intertrochanteric osteotomy)

59. Femoral fracture Either femoral neck fracture or subtrochanteric fracture following insitu fixation of SCFE Likelihood of this complication can be decreased by avoiding drilling unnecessary holes in the bone during surgery and by avoiding overzealous reaming of femoral neck

60. FAI One of the cause of FAI is SCFE that has healed in less than suitable anatomic position. Literature is unclear about how much posterior angulation can be accepted during initial treatment or even how much angulation later will cause FAI Anterior head-neck offset angle (Notzli alpha angle) has been reported to correlate most strongly with FAI Greater the Notzli angle, the smaller the arc of motion required to cause cam type impingement on the acetabular rim.

61. The cam effect in which the femoral head or screw head abuts the acetabular labrum and the pincer effect in which the acetabular rim impinges on the femoral neck have both been described in adults who had treatment of SCFE as adolescents. FAI can be identified by arthroscopy and MRI; plain crosstable lateral radiographs Valgus osteotomy or the Imhauser procedure has been recommended after insitu pinning to avoid acetabular impingement.

62. References Apley’s system of orthopaedics and fractures, 9th edition. Campbell operative orthopaedics,12th edition. orthobullets.com Internet sources