Based on favorable outcomes from long-term studies [3
], the standard treatment for mild SCFE has become in situ pinning. More recently, this protocol has been called into question by reports that even mild slips may lead to early acetabular labrum and cartilage damage [10
]. Reports from several centers suggest treatment of mild SCFE should not only prevent further slippage, but also address potential impingement [12
]. The purposes of this article were to describe a novel treatment protocol for mild SCFE, report our initial experience with this technique, and present clinical evidence for and a conceptual basis to support additional surgical intervention after mild slips.
Our study is limited by only three patients and short followup. We therefore cannot say whether this treatment protocol will produce superior long-term function or reduce the risk of OA compared to in situ pinning alone. However, we believe the evidence [13
] indicating mild slips produce cartilage damage warrants intervention before patients become symptomatic and irreversible articular injury has resulted. In addition, the pathomechanical understanding of how this damage occurs [17
] compels us to consider such treatment even before long-term results have accumulated. Although the natural history of articular cartilage damage is not clearly understood, we believe it is likely to progress unless the offending lesion is eliminated.
In support of in situ pinning alone, Boyer et al. [3
] presented a series of 149 slips followed an average of 31 years. For patients treated without realignment, Iowa Hip Rating scores were 93 for mild and moderate slips and 85 for severe slips. Moderate or advanced arthrosis was seen in 6 of 39 mild slips, 3 of 22 moderate slips, and two of five severe slips. The realignment group fared worse with average Iowa Hip Rating scores of 90, 70, and 73 and substantial arthrosis in one of two, 14 of 18, and 21 of 24 hips. At mean followup of 41 years, this same patient population was reevaluated [8
] demonstrating Iowa Hip Rating scores of 89, 81, and 73 and showing that12% of mild slips required additional surgery which was not specified.
In our opinion, however, there are limitations of these often-cited studies [3
]. First, the scoring system [16
] used inadequately reflects moderate functional and motion losses that are important to this active population. Second, the 15% reported rate [3
] of moderate or advanced arthrosis in subjects averaging 45 years is high when compared to a prevalence of 1.7% in those aged 45 to 49 [9
]. Additionally, intermediate followup studies suggest patients have pain and functional limitation after mild SCFE [10
]. Fraitzl et al. [12
] evaluated 16 hips with slip angles ≤ 31º at average followup of 14.4 years. Tegner and Lysholm scores averaged 5.2 with nine subjects scoring 4 or less. This compares to an average score of 6.5 for similarly-aged asymptomatic volunteers [4
]. Another series [10
] of 49 hips treated with in situ pinning alone with an average followup of 6.1 years identified 15 painful hips, including 10 of 30 mild slips.
More importantly we believe, there is growing evidence that shows substantial articular damage after mild SCFE. Over 15 years ago, Futami et al. [13
] assessed five hips arthroscopically at the time of in situ pinning. Anterosuperior acetabular cartilage erosion was present in all four hips visualized. Slip angles for these hips were 20°, 22°, and 31°; that for the fourth hip was not reported. Leunig et al. [17
] treated 14 hips with prior SCFE and observed impingement in all hips. Acetabular cartilage damage was observed in 12 hips, including all three mild slips, 8 of 10 moderate slips, and the one severe slip. In mild to moderate slips, the metaphysis was observed to enter the joint, whereas in severe slips, the prominent metaphysis abutted the acetabular rim, preventing its entry into the acetabulum. In a subsequent evaluation of 30 hips [19
], acetabular cartilage damage was graded as 2.3, 2.2, and 1.8 for mild, moderate, and severe slips. Most recently, a series [25
] of 39 painful hips treated by dislocation revealed cartilage damage in 6 of 8 mild, 16 of 20 moderate, and 10 of 11 severe slips.
Consistent with this clinical evidence, computational studies have provided a clearer understanding of how articular damage occurs after mild SCFE. Rab [24
], using a volume/surface model, identified the same two types of impingement that Leunig et al. [17
] observed clinically. Rab termed them “inclusion” and “impaction” and proposed that “inclusion” may be more damaging. A CT modeling study of actual slips [22
] demonstrated impingement in all slip severities.
Early followup of the first three hips treated with this protocol demonstrated asymptomatic patients, improved hip ROM, and no clinical evidence of impingement. Radiographic assessment showed increased epiphyseal-metaphyseal offsets and decreased alpha angles. Obviously, this combination of procedures can only be used for mild epiphyseal tilt and translation; for larger deformities, even substantial osteoplasty would not eliminate impingement and might critically decrease the neck’s structural integrity. Additionally, osteoplasty neither realigns the epiphysis with the femoral shaft nor increases the articular bearing area. Therefore, we recommend capital realignment for moderate and severe SCFE [19
We believe the ultimate goal of SCFE treatment should be to intervene before irreversible joint injury occurs and that, for mild SCFE, in situ pinning with immediate arthroscopic osteoplasty can reduce or even eliminate hip impingement, which is reported to lead to osteoarthritis of the hip [14
]. We recognize, however, that only long-term followup with comparison to a control group treated with in situ pinning alone can demonstrate whether our proposed technique decreases subsequent articular damage. Although we advise performing these procedures concomitantly, osteoplasty may be performed at a subsequent date. This is particularly true if the pinning surgeon is not a proficient hip arthroscopist, given that arthroscopy following an epiphyseal slip is technically demanding.