1 Introduction

Albers-Schonberg originally described osteopetrosis, often known as “marble bone disease,” in 1904. Osteopetrosis is a collection of illnesses with increased bone density on plain radiographs that are clinically and genetically heterogeneous. Patients are prone to pathological fractures, non-union, and osteomyelitis due to failure of remodelling due to osteoclast dysfunction.^1,2

For, femur fractures in osteopetrosis, several experts urge conservative therapy.^2,3 The healing and remodelling of fractures in osteopetrosis are unpredictable due to a defect in osteoclastic function, which may increase rehabilitation time and nursing care for the patient. As a result, the majority of the authors recommend that these fractures be treated surgically. But, due to the obliteration of the medullary canal and high bone density, surgical therapy is generally laden with increased difficulties and higher postoperative complications.

There is limited literature on the technical difficulties and pitfalls of operative procedures in patients with osteopetrosis. We report a case of shaft of femur fracture in an 11-year-old male child, who was managed successfully with open reduction and internal fixation with locking compression plate using a machine drill bit and the tips and tricks to prevent complications in these patients.

2 Case report

An 11-year-old male patient presented with pain in the left thigh with the inability to bear weight on the limb following a fall from stairs. He had no prior history of fractures in the past. Family history revealed a similar history of fracture in the elder sibling following trivial trauma and was diagnosed with osteopetrosis (Fig. 1).

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Fig. 1 Plain radiograph of Elder sibling showing B/L Subtrochanteric fracture.

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On general examination, the patient had a triangular-shaped face (Fig. 2), Blue sclera and Crossbite of the anterior teeth. Local examination of the left lower limb showed that there was diffuse swelling over mid-thigh with tenderness. A radiograph of the left hip with femur was taken. It revealed a simple oblique midshaft femur fracture, with thickened cortical boundaries and reduced intramedullary canal diameter with Erlenmeyer deformity of the femur (Fig. 3). A skeletal survey revealed generalized increased bone density and obliteration of the medullary cavity in other bones (Fig. 4).

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Fig. 2 Abnormal Facies - Showing anterior cross bite of the teeth and triangular facies.

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Fig. 3 Radiograph of left thigh showing oblique shaft of femur fracture.

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Fig. 4 Skeletal Survey Fig. 4A Skull - AP and Lateral radiograph Fig. 4B Whole Spine - Lateral radiograph Fig. 4C Chest - AP radiograph Fig. 4D Upper Limb - AP radiograph.

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Hematologic examination showed Haemoglobin of 9.5 ​gm%. Red cell indices, iron profile, serum calcium, serum phosphate, Intact PTH, urinary sodium and potassium were normal. Vitamin D levels were low with raised ALP and S. creatinine kinase levels. The patient was diagnosed with a case of osteopetrosis based on the history, radiological and laboratory findings.

2.1

2.1 Surgical technique

After taking the patient's consent, the patient was taken for surgery under general anaesthesia in a lateral position. We used a standard lateral approach to the femur (Fig. 5). The fracture was reduced under direct vision and the fracture was provisionally secured with the help of a reduction clamp. We made a pilot hole with the help of a 2.7 mm machine drill bit (Fig. 6) followed by a 3.2 mm drill bit. Regular cooling with saline was done to prevent thermal necrosis. The purchase of screws was excellent without any incidence of drill bit breakdown in our case. The skin was closed in layers over a drain.

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Fig. 5 Intraoperative images showing Incision, Fracture site, Fracture fixation with plate.

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Fig. 6 Machine drill bit.

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Post-operative period: Post-operative radiographs were done (Fig. 7) and wound inspection was done on the second post-operative day. There were no signs of infection. Sutures were removed on the 14th day post-operatively. The patient was advised strict non-weight bearing for 6 weeks with a high groin slab in-situ. He has advised weight-bearing mobilization at 6 weeks after radiographs showed signs of bony union. At the last follow-up of 8 months, the patient was standing and walking independently and with no sign of infection and complete bone healing on radiographs (Fig. 8).

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Fig. 7 Postoperative radiography showing adequate plate fixation.

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Fig. 8 At Follow up Fig. 8A Clinical images at follow up - Standing independently Fig. 8B Radiograph at follow-up showing fracture union.

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3 Discussion

Osteopetrosis is a rare hereditary disorder of the musculoskeletal system where there is increased bone density due to osteoclastic dysfunction. Management of femur fracture in osteopetrotic patients is controversial. Many studies have suggested conservative therapy for the management of femur fractures in patients with osteopetrosis. Since these fractures are prone to delayed union due to defective osteoclastic function and these patients have to be bedridden for a significant amount of time. Surgical management is ideal for these patients as it provides better reduction and optimal nursing care to the patient.

The management of shaft of femur fracture in an 11-year-old is quite standard with literature favouring operative management either with TENS nailing or submuscular plating depending upon the fracture pattern. But since the medullary canal is obliterated in these patients and the bone is dense, we planned for open reduction with internal fixation using a locking plate. But operative management is associated with problems like combined brittleness and hardness of the osteopetrotic bone, which causes instrument (the drill bit and reamer) failure and screw breakage, iatrogenic fracture, thermal necrosis, prolonged operation time, increased blood loss, and increased risk of infection.^1,2,4–6 We report the successful management of acute femur fracture in A 11-year-old child and the tricks and tips to circumvent these problems.

Drilling converts mechanical work energy into thermal energy leading to a transient rise in temperature of adjacent bone and soft tissues to above normal physiological levels. Drilling resistance increases with bone density, resulting in heat necrosis of the bone and numerous drill bit breakage. According to Eriksson et al.,⁷ viability, structural properties and according to Bonfield et al.,⁸ mechanical properties of healthy bone may be compromised due to exposure to elevated temperatures. Excessive temperatures level can result in necrosis of bone, thereby hampering the osteogenic potential. This dead bone is resorbed by osteoclasts and which may lead to catastrophic consequences for rigidity of bone screws and pins, and overall result in the failure of fracture fixation. However, the osteoclasts are defective in osteopetrosis leading to higher chances of osteomyelitis apart from bone marrow suppression due to obliterated medullary canal. In 2010, Amit et al. conducted a review of the available literature (4 femoral neck fractures and 21 per-trochanteric fractures) on the surgical treatment of OPF in adults, reporting a non-union rate of 12%, an infection rate of 12%, the hardware failure rate of 29%, reoperation rate of 29%, and periprosthetic fracture rate of 14%.⁹

These problems, according to Imran et al., could be addressed by using a “high-speed steel drill bit."⁴ Previously, Sen et al. had described the use of a metal-cutting drill bit to make the pilot holes followed by a standard 3.2-mm drill bit in their study.² The use of metal-cutting drill bits made the job easier and also decreased the incidence of thermal necrosis. Ramiah et al. used a tungsten carbide drill bit for the fashioning of the medullary canal in a patient with a peri-implant femoral neck fracture.¹⁰ The tungsten carbide drill bit also reduced surgical time and the extent of necrosis. Kunnasegaran et al. and Strickland et al. obtained similar results suggesting the use of power drills and/or high-speed burrs to recreate a medullary canal.¹ We used a machine drill bit in this patient for making the pilot hole. Using a machine drill bit helped us to reduce the operative time and thermal necrosis. Moreover, it was inexpensive compared to other bits mentioned in the literature. However, one should be mindful of the fact that there will be a sudden loss of resistance with drilling using a machine bit which may injure the soft tissue. We recommend that drilling should be done under fluoroscopic control.

Due to the brittle nature of the osteopetrotic bone, these patients are prone to refracture and hardware failure.³ Slow and non-aggressive post-operative rehabilitation protocol should be followed with plating as weight-bearing exercises could lead to stress concentration, screws loosening, and implant failure. That is why we kept the patient immobilized in a high groin cast till a radiological sign of union was visible.

According to our experiences, there were several key points for successful treatment of Osteopetrotic femur fracture.(i)Proper preoperative planning with operative technique, choice of implant and choice of the drill bit.(ii)Plating is a better modality than nailing for femur fracture.(iii)Locking plate is reliable for fixation of shaft femur fracture in these patients.(iv)Intermittent and progressive drilling procedures with continuous saline irrigation are necessary.(v)Machine drill can significantly reduce the complication rate.(vi)Non-aggressive postoperative rehabilitation is key for management.

4 Conclusion

Locking Compression plating is an effective treatment option for shaft femur fractures in patients with osteopetrosis. The use of a machine drill bit can significantly reduce the operative time and postoperative complications by decreasing thermal necrosis.

Ethics approval

Approval from the institutional ethics committee was not required for this case report.

Consent to participants

Not Applicable.

Consent to publish

All authors have read the final prepared draft of the manuscript and approve this version, in its current format if considered further for publication.

Financial support and sponsorship

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Authors contributions

V.M - Planning of report, literature search, writing the manuscript, Corrspondence.

V.G - Literature search, Manuscript preparation.

S.S - Quality assessment of the included studies, writing and revising the manuscript.

A.G - writing and revising the manuscript.

V.S - Data management, outcome assessment, revising the manuscript.

Availability of data and materials

All included studies used in this retrospective study are available online. The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Data regarding this study is not available in any electronic databases.