Keywords
osteogenesis imperfecta - revision hip arthroplasty - bone fragility - complex total
hip arthroplasty
Osteogenesis imperfecta (OI) is a group of autosomal dominant collagen type I (COL1A1
and COL1A2) connective tissue disorders commonly associated with bone fragility, deformity,
and fractures.[1]
[2] Other common manifestations of OI include blue or gray sclera, dentinogenesis imperfecta,
joint hypermobility, hearing impairment, and cardiovascular and central nervous system
complications.[1]
[2]
[3] While certain genetic variants of OI are intrauterine lethal, others can have life
expectancies comparable with that of the general population.[4]
[5] Furthermore, advancements in medical and surgical treatments for OI have only enhanced
their longevity and quality of life.[6] However, with their increasing life expectancy, a growing population of ambulatory
OI patients is presenting for the treatment of end-stage osteoarthritis in their hips
and knees.[7]
Primary total hip arthroplasty (THA) is challenging in patients with OI due to poor
bone quality, anatomical deformities, and soft tissue laxity. Additionally, with a
prevalence between 0.3 and 0.8 per 10,000 births, these patients present as rare and
technically challenging surgical THA candidates.[1]
[8]
[9]
[10] In Krishnan et al's 2013 case series of six OI patients undergoing primary THA,
THA survival rates were reported to be only 16% (1/6) at a median time of 5.2 years
(range: 2.8–11 years), demonstrating the high revision burden of these patients.[11] Given that revision surgery comes with more frequently encountered anatomical deformities
and excessive bone loss, it is imperative to understand the outcomes associated with
revision THA to further inform the surgical management of patients with OI. Very few
cases of revision THA in adult patients with OI have been reported to date. Here we
present a report on a patient with OI undergoing a second revision THA.
Case History
A 62-year-old male with a history of OI presented to our clinic for the evaluation
of right hip pain localized to the groin for the past 5 months. He initially underwent
right primary THA 22 years ago for symptomatic osteoarthritis. This was revised 14
years later secondary to pain from aseptic failure. The patient had improved pain
until approximately 5 months prior to the presentation, when he began having start-up
pain in the right hip and worsening pain with ambulation. The pain was managed conservatively
with ambulatory assist devices, physical therapy, and anti-inflammatory medication.
However, he reported continued deterioration. At the time, he ambulated with a cane
for five blocks, avoided going up and down stairs, was unable to use public transportation,
and had difficulty reaching down to put on his right sock and shoe. He did not smoke
and had less than one drink per week. His history was also significant for severe
scoliosis and multiple fractures that required surgical intervention. Most recently,
the patient suffered a left wrist fracture requiring open reduction internal fixation
(ORIF). He has also undergone ORIF for a left hip fracture more than 30 years ago
and required surgery on his bilateral elbows, right femur, and left shoulder. His
OI was previously managed with ibandronate, but he has discontinued the medication
for some time. The remainder of his medical history is unremarkable.
Physical Examination and Radiographic Assessment
On physical examination, the patient weighed 71 kg with a body mass index of 25.2 kg/m2. He ambulated with the assistance of a cane and had an antalgic gait. A well-healed
surgical scar was present over the patient's right hip. He endorsed tenderness to
palpation over the right greater trochanter. Range of motion of the right hip was
limited to 60 degrees of forward flexion, 20 degrees of external rotation, 10 degrees
of internal rotation, 10 degrees of abduction, and 10 degrees of adduction. There
was no leg length discrepancy noted on clinical examination. Radiographic imaging
of the right hip demonstrated a loose cemented right THA in varus alignment with evidence
of protrusion through the lateral femoral cortex ([Fig. 1]). Substantial proximal femur remodeling and heterotopic ossification were also visualized.
The patient was referred from an outside institute where an infection work-up was
conducted, including C-reactive protein and erythrocyte sedimentation rate, and the
results were conveyed to us prior to the patient's preliminary visit. After extensive
discussion regarding risks and benefits of the surgery, the patient elected to proceed
with right revision THA.
Fig. 1 Preoperative imaging. Anteroposterior, lateral, and lower extremity radiographs demonstrating
a previous revision total hip arthroplasty with distal stem migration into a pseudocanal.
Operative Intervention
After induction of general anesthesia, the patient was turned to the lateral decubitus
position. A modified Kocher–Langenbeck incision was made, and the soft tissue was
dissected to expose the implant. Intraoperative examination was significant for a
loose femoral stem. Using the same implant system, the acetabular liner was exchanged
and upsized from 32 mm to 36 mm with an elevated lip (StelKast). The 58-mm cup from
the prior revision was retained due to the low quality of bone. After the stem was
safely extracted without fracture, a prophylactic wire was placed distally to prevent
fracturing of the femur while reaming. Cement was removed safely from the canal with
the help of cement removal tools and osteotomes (Moreland set, DePuy). Fluoroscopic
imaging was used to assess placement of the reamer in the proper canal and confirmed
that no disruption occurred.
Due to severe deformity of the femur, an osteotomy was performed and the femur was
realigned over the long stem that was placed. After successful trial reduction, the
final stem, a 300-mm titanium tapered fluted monoblock stem (REDAPT, Smith & Nephew)
with high offset and a 36-mm femoral head, was placed. A second cable was placed distally,
and multiple no. 5 Fiberwires (Arthrex) were passed to secure the osteotomy. The hip
was reduced, taken through range of motion, and found to be stable. Intraoperative
X-rays were obtained and reviewed prior to closure of the wound. No fractures were
visualized, and all implants were in an acceptable position. The remainder of the
surgery proceeded in standard fashion and without further complications. While we
routinely take an intraoperative aspiration for cell count and differential, in this
case we could not obtain intraoperative joint fluid.
The patient was mobilized with physical therapy with 50% partial weight-bearing on
postoperative day 1. His hospital course was otherwise uncomplicated, and he was discharged
home on postoperative day 4.
Postoperative Care
At the patient's first postoperative visit, radiographs demonstrated that the implant
remained in a good position without evidence of loosening ([Fig. 2]). He was cleared for full weight-bearing as tolerated 6 weeks postoperatively. By
3 months, the patient was ambulating independently without an assistive device. Forward
flexion of the hip was improved to 90 degrees. Follow-up standard radiographs demonstrated
a well-fixed, well-positioned right THA. At his most recent follow-up, 14 months postoperatively,
the patient had no complaints regarding the right hip and he continued to ambulate
freely ([Fig. 3]).
Fig. 2 Three-week postoperative imaging. Anteroposterior pelvis and cross-table radiographs
demonstrating a well-fixed, well-positioned right total hip arthroplasty.
Fig. 3 Fourteen-month postoperative imaging. Lower extremity and anteroposterior pelvis
radiographs demonstrating a well-fixed, well-positioned right total hip arthroplasty.
Discussion
Given the incidence of posttraumatic and osteoarthritis in adults with OI, an increasing
population of patients who fail nonsurgical interventions are electing to undergo
surgical management for their arthritis. However, in this patient group, the complication
rate associated with hip arthroplasty is substantially higher than that of the general
population, and implant longevity is diminished.[12] Therefore, prior to surgical intervention, it is imperative that several risk factors
are considered, including the quality of the underlying bone, the alignment of the
preoperative limb, and any abnormal pelvic or femoral anatomy. Further understanding
of which patients require revision surgery can also help inform surgical planning
and the management of this complex population, as well as providing for an adequate
fund of knowledge to appropriately manage patient expectations.
One anatomical defect, protrusio acetabuli, was found to be significantly associated
with THA revision and is commonly observed in 29 to 66% of patients with OI.[11]
[13]
[14] In a case series of six hips with OI by Krishnan et al., 83.3% (5/6) of primary
THAs required revisions.[11] Among this group, patients with preoperative acetabular protrusio were significantly
more likely to be revised than those without. This study also found a greater mean
number of revisions among patients with a prior femoral or acetabular fracture compared
with those without. Papagelopoulos and Morrey also described a series of five THAs,
and although only one patient in this study had a reported failure, the patient also
had protrusio.[7] While this anatomical defect is less commonly seen in patients without metabolic
bone disease, protrusio acetabuli can be secondary to inflammatory causes, seen in
up to 15% of patients with rheumatoid arthritis of the hip and 33% of patients with
ankylosing spondylitis. It is also estimated to occur in approximately 5% of patients
with osteoarthritis.[15] However, survivorship of primary THA implants in these patients is reported between
73 and 100%, with a maximum follow-up of 20 years.[16] While no large studies have been conducted on the rate of revision THA in patients
with OI and protrusio, current literature suggests an increased failure rate among
these patients. Although the presence of confounding variables makes it more difficult
to reach a definite conclusion, acetabular protrusion adds complexity to an already
technically challenging operation and is important to consider preoperatively, if
present. In our case, the patient did not have acetabular protrusio but did have a
remote history of a right femoral fracture and two prior arthroplasty surgeries. The
patient's poor bone quality and prior revision surgery, known risk factors for aseptic
loosening, likely also contributed to this second failure.
Another important consideration prior to surgical intervention is intraoperative fracture,
with rates as high as 50% reported in OI patients undergoing primary THA.[11] A larger study of osteoporotic patients found the intraoperative fracture rate to
be approximately 4% after hip replacement, with even higher rates reported in revision
surgery.[17]
[18]
[19] This would suggest a similarly increased risk in patients with OI who have poor
bone quality in addition to other anatomical defects, though no studies have demonstrated
this effect. These studies also show, in the general population, that risk factors
for intraoperative fracture in THA include osteoporosis, revision surgery, stem length,
low ratio between the cortical and canal diameters, metabolic bone disease, and the
use of noncemented, press-fit implants.
There is no general agreement on the most appropriate type of implant to minimize
the incidence of intraoperative fracture, bone loss, and implant failure among this
high-risk population. Papagelopoulos and Morrey reported satisfactory results with
cemented implants, with only one patient requiring revision and no report of intraoperative
fracture.[7] Krishnan et al used only noncemented stems in primary surgery, resulting in 50%
incidence of intraoperative fracture and 16% survival rate of the implant in primary
THA at a median time of 5.2 years. However, the authors suggested the use of customized
femoral components to minimize fracture in patients with narrow canals and thin cortices.[11] Among the general population, the highest rate of intraoperative fracture is reported
at 20.9% in patients undergoing revision THA with noncemented implants compared with
3.6% in revision THA with cemented implants.[18] Additional data from a Scandinavian arthroplasty registry showed that in patients
with osteoporosis, there was an 8.8 times increased risk of early periprosthetic fractures
with the use of noncemented stems.[20] However, due to anatomical limitations, cemented stems may be difficult to centralize,
preventing an adequate cement mantle from being placed around the prosthesis.[11] A cementless, fluted tapered titanium monoblock stem was chosen for this case as
the surgeon has vast experience using this stem in complex femoral reconstruction.
Additionally, previous work has shown good outcomes in complex cases using monoblock
stems.[21]
[22]
[23]
[24] Regardless of implant type, precautions must be taken to limit intraoperative fractures.
Throughout this case, several precautions were taken to ensure a successful outcome
and minimize the risk of intraoperative fracture. With adequate soft tissue release
and exposure, the previous stem was safely extracted and a prophylactic wire was placed
distally prior to reaming. Given the presence of a known pseudocanal, fluoroscopic
imaging was used to assess placement of the guidewire, and flexible reamers were used
to reestablish the femoral canal. A corrective osteotomy was also performed to avoid
varus placement of the stem and an intraoperative fracture. Due to the increased risk
of the procedure, final intraoperative fluoroscopy images and portable X-rays were
taken and reviewed prior to completion of the operation to confirm that there were
no fractures and the implant was correctly seated. Careful planning and the use of
additional precautions may decrease the high rate of intraoperative fractures in these
high-risk cases.
In addition to careful surgical planning, bone health is an important factor for the
success of both primary and revision THA and should be addressed prior to surgical
intervention. One suggested medical intervention to address bone quality is bisphosphonate
therapy. While bisphosphonates do not address the underlying bone quality issues in
OI, they do increase bone mineral density, decrease fracture rates, improve pain,
and are a common medical treatment employed in this population.[25]
[26]
[27] Studies on patients with osteoporosis have shown that bisphosphonates administered
postoperatively are effective at reducing periprosthetic bone resorption in the first
year after surgery, commonly seen after hip replacement.[28]
[29]
[30] In a large retrospective cohort study in the Danish population, there was a 59%
reduced risk of revision surgery if bisphosphonates were started after arthroplasty
and continued for at least 1 year postoperatively.[31] Use of bisphosphonates was also found to lower the fracture risk among THA patients
who received the medication for at least 6 months prior to fracture, both as primary
prevention and among patients who had experienced a previous osteoporotic fracture.[32] Several additional studies have shown similar positive effects in patients taking
bisphosphonates for a minimum of 6 months, which may persist as long as 18 to 72 months
after discontinuation.[33]
[34]
[35]
[36] While several studies have used a 6-month minimum duration of bisphosphonate treatment,
the optimal timing and duration remain to be determined.
Although there is an initial decrease in the overall fracture risk with bisphosphonate
therapy, with evidence to suggest improved bone mineral density and decreased revision
rate after total joint arthroplasty, long-term therapy with these medications are
associated with atypical femoral fractures, and patients need to be monitored carefully.[37] In this case, the patient was taking ibandronate prior to his revision THA, though
it was discontinued more than 1 year prior to surgery. Due to the rare incidence of
the disease, no studies have looked at the effect of bisphosphonate therapy on joint
arthroplasty in patients with OI, but there is potential benefit for use of this therapy
in the surgical setting.
Conclusion
Improvements in both medical and surgical interventions in patients with OI have extended
the life span of these patients and helped to improve quality of life. As THA is used
more frequently in this population, further understanding of how these and other factors
influence the likelihood of required THA revision will help ensure that the right
patients are undergoing surgical intervention and the correct precautions are taken
to minimize complications and decrease implant failure.
