Keywords
hip dislocation - arthroscopy - loose body - labral tear
Introduction
Consensus exists about emergency treatment of a pediatric hip dislocation. The hip
may remain nonconcentric after reduction because of an intra-articular bony or cartilaginous
loose fragment from the femoral head, an interposition of the labrum complex, or other
soft tissue interpositions.[1]
[2]
[3] Different open reduction techniques have been described if concentric reduction
fails, such as a posterior Kocher–Langenbeck approach to access the posterior joint
space[1] or a surgical hip dislocation[4]
[5] to fully access the articular joint space. Due to an increased arthroscopic treatment
of the adult hip, hip arthroscopy has been extended to include the pediatric population
as well.[6]
[7]
[8]
[9] There have been a few reports focusing on arthroscopic treatment after a pediatric
hip dislocation.[8]
[10]
[11]
To add to the current literature, we will report a case of arthroscopic treatment
of an intra-articular osteochondral fragment and labral tear in a 13-year-old boy.
Patient and Technique
We report the case of a 13-year-old boy, who sustained a posterior left hip dislocation
during a soccer duel. His weight was 47 kg and height was 152 cm. After an initial
anteroposterior (AP) view, the hip was emergently reduced under sedation on the day
of trauma in another surgical department by a pediatric surgeon. Because the postreduction
AP view of his left hip showed a nonconcentric reduction, a computed tomography (CT)
scan ([Figs. 1A] and [B]) and a magnetic resonance imaging (MRI) ([Figs. 2A] and [B]) of his left hip were performed. On CT and MRI scans, an intra-articular bony fragment,
which was detached from the femoral head, was identified. Five days after the reduction,
the patient was referred to our Department of General and Trauma Surgery for further
treatment. The reasons for the delay of the referral are unknown. On physical examination,
the patient exhibited sensory and motoric deficits to his sciatic nerve with two-fifths
restricted strength of dorsal flexion of his left foot and hypaesthesia in the areas
of the common peroneal and tibial nerves.
Fig. 1 (A and B) The computed tomography (CT) scans show the intra-articular bony fragment which
caused the nonconcentric reduction of the left hip.
Fig. 2 (A and B) The magnetic resonance imaging (MRI) shows the nonconcentric hip with intra- and
periarticular edema.
After careful evaluation of the images and consideration of the possible operative
approaches, we decided to treat the patient arthroscopically. Operative treatment
was performed on the sixth day postinjury. The patient was placed supine on a fracture
table. Traction on the left leg and countertraction on the right leg was carefully
applied until the joint space was adequately widened. Under fluoroscopic guidance,
the hip was penetrated with a trocar needle for an anterolateral port and a 70° arthroscope
was inserted over a guided wire. An additional anterior working port was established.
The intra-articular hematoma was sectioned and debrided with a shaver. We were able
to identify an osteochondral fragment in the fovea attached to the posterior labrum
complex ([Fig. 3]). A grade 3 chondral lesion based on the Outerbridge classification system (grade
0–4)[12] was seen on the femoral head as well as a small contusion of the posterior acetabular
rim.
Fig. 3 Small intra-articular osteochondral fragment, which was detached from the femoral
head.
We additionally identified a tear at the posterior labral complex, which led to complete
enfoldment of the posterior labrum. Both injuries were responsible for the nonconcentric
reduction. With a biter the osteochondral fragment was removed, which during dislocation
had obviously detached from the femoral head. Careful debridement of the labral tear
was performed. Furthermore, we were able to manipulate the posterior labral complex
with a hook until it was unfolded ([Figs. 4A–C]). Postreduction the labrum appeared to be stable without repeat enfoldments, and
therefore no further suture anchors or wires were deemed necessary. Operative procedure
time was 65 minutes. Postoperatively concentric hip reduction was confirmed with an
AP radiograph of the left hip ([Fig. 5]). The hip was clinically stable under full range of motion. The patient was instructed
to toe tip weight-bearing for 6 weeks with restriction of hip flexion to a maximum
of 60°. Eight weeks postsurgery, the patient was able to fully weight-bear without
any pain or discomfort and had regained full range of hip motion. Remission of neurologic
deficits was also noted.
Fig. 4 (A, B, and C) Intraoperative images showing the enfolded labrum, which was reduced with careful
manipulation with a hook. The labral complex was stable after reduction.
Fig. 5 Anteroposterior (AP) radiograph shows the concentric reduction of the hip after arthroscopic
treatment.
Discussion
Careful evaluation of concentric reduction is essential after closed reduction of
a dislocated hip. Soft tissue interpositions, incarcerated labral tears, or intra-articular
loose bodies can be frequently found postreduction.[11] Further imaging is required. Especially in the pediatric population, the MRI investigation
is preferable to CT scan. In a series of 40 patients under 16 years old, Mayer et
al reported that all surgically confirmed soft-tissue injuries were preoperatively
identified on MRI, which also offered the advantage of absence of radiation in that
age group.[13] CT scan may especially lead to underestimation of an osteochondral lesion at the
posterior wall.[13]
[14] In the present case, a tear at the posterior labral complex, which lead to complete
enfoldment of the posterior labrum, and an additional osteochondral fragment resulted
in the nonconcentric joint after closed reduction of the hip. Similarly, treatment
of an incarcerated acetabular labrum following reduction of a traumatic hip dislocation
has been effectively reported with either refixation or excision of an osseo-labral
fragment via hip arthroscopy in adults.[15]
In the pediatric population, hip arthroscopy was initially used for various diseases,
such as Perthes disease, slipped capital femoral epiphysis, or neuropathic subluxation.[16] Its use has been widened to include posttraumatic disorders. Morris et al reported
seven patients (aged 8–17 years) who were arthroscopically treated after a traumatic
hip dislocation. They described an entrapment of the posterior labrum with or without
an attached bony fragment from the posterior acetabular wall as the predominant and
consistent pathology in these patients. Removal of the fragment and reduction of the
soft tissue without repair of the soft tissue or bony fragments was arthroscopically
performed in all children. Concentric, stable reduction without the occurrence of
an avascular necrosis, recurrent instability, or pain on follow-up was reported.[8] Intraoperative pathology reported in their series, was similar to the findings in
our patient, except for the origin of the bony fragment, which belonged to the femoral
head in our patient. Similar findings were reported by Wylie et al who performed hip
arthroscopy after hip dislocation in 12 patients younger than 25 years (11–25 years).
Eight patients were found to have intra-articular loose bodies, three patients with
degenerative labral injuries, three full-thickness tears of the acetabular labrum,
one separated labrum, and one incarcerated. In two patients, femoral articular cartilage
injuries, and in five patients, acetabular cartilage injuries were present. A torn
of the ligamentum teres was noted in all patients. All injuries were addressed arthroscopically.[11] In the present case, with an Outerbridge III defect, presenting a fissuring at the
level of the subchondral bone, we decided to remove the fragment without further surgical
intervention such as chondroplasty or microfracture. Kocher et al described chondroplasty
of the acetabulum or femoral head in 10 patients (< 18.9 years). In patients with
Outerbridge IV degenerative changes, no improvement of the Harris Hip Score was reported
after the procedure.[17] Philippon et al suggested microfracture for Outerbridge IV full-thickness damages
in pediatric patients with femoroacetabular impingement.[18] They described microfracture for chondral defects in nine professional athletes
after hip dislocation.[19] Similar to the mentioned studies, we were able to fully address the pathology in
the 13-year-old boy using an arthroscopic approach without the necessity to convert
to an open approach or further intervention. The hip remained stable after the procedure.
Timing of the operative intervention is critical, in our patient we decided to schedule
the arthroscopy for the next day after referral. The operation should be performed
by a team, which is skilled in hip arthroscopy. In general we would not suggest a
delay of more than 1 to 2 days after diagnosis of the nonconcentric reduction in patients
with a small intra-articular bony fragment and labral tear. If gross dislocation persists,
an immediate operation is indisputable.
Even though arthroscopic treatment appears to be less invasive, it leaves smaller
scars compared with open approaches or surgical hip dislocations, and complications
should not be underestimated or ignored. Complications may be due to direct manipulation,
such as damage to the femoral or acetabular cartilage, nerve injuries, during insertion
of the instruments, or secondary to traction to the hip during the procedure or fluid
instillation. In the adult population, the incidence of heterotopic ossification after
hip arthroscopy is reported between 1.0 and 6.3%[20] and the incidence of deep vein thrombosis has been reported to be 1.4%.[21] Kocher et al reported three cases of pudendal nerve paresthesias which resolved
spontaneously and one broken guidewire, which was retrieved arthroscopically.[17]
No standardized protocols regarding the postoperative management exist. Our patient
was instructed to toe tip weight-bearing for 6 weeks with restriction to a maximum
hip flexion of 60°. Wylie et al began physiotherapy at 2 weeks, his patients started
with touchdown weight-bearing for 2 weeks with partial weight-bearing for another
2 weeks and discontinuation of the crutches at 4 weeks. Hyperextension and external
rotation of the foot was permitted for 6 weeks. Full range of motion was allowed between
6 and 12 weeks.[11]
Conclusion
In our experience and review of the literature, labral tears and intra-articular bony
fragments, which lead to nonconcentric reduction after a pediatric hip dislocation,
can be safely and successfully addressed with a hip arthroscopy. Removal of bony fragments,
reduction, sutures, or labral resections can be performed to gain a stable reduced
hip. The procedure should be performed by experienced surgeons, who are capable of
converting to an open approach, although the possibility is likely to be minimal.
