1.1 Patients
Using the orthopaedic trauma files in our institute, data were gathered for this retrospective study. Initially, data from a total of 657 patients who had suffered from intra-articular distal femur fractures between May 2014 and Feb 2019 were identified through searching from a prospective orthopaedic database, out of which there were 19 cases (2.89%) with Hoffa fractures. Patients who had undergone conservative treatments, open or pathological fractures, any additional supra-condylar or inter-condylar fractures, severe neurovascular injury and any previous surgery of the involved knee were all excluded. In the end, a total of 13 patients who had suffered Hoffa fractures were enrolled in the study. All patients underwent surgery with DFCLP fixation alone or in combination with cannulated screws followed by early active rehabilitation. The DFCLP and cannulated screws were provided by Jiangsu Jinlu Medical Company. Study subjects include 13 patients, the attendance on the follow-up appointments were perfect and no patients dropped out. Our work complies with the STROBE criteria.
Before the surgery, the involved leg was fixed with plaster to avoid further injury. Meanwhile, X-ray, MRI, and CT scanning were performed to determine the fracture types and the conditions of soft tissues. The patient sample comprised of 9 males and 4 females with an average age of 49.9 years (ranging from 26 to 64 years old) at the time of surgeries. The fracture side, mechanisms of injuries, time of operation and follow-up period were all recorded. All fractures were closed and categorised according to the Letenneur descriptions[7]. The fractures included 10 lateral (77%) cases and 3 medial cases (23%). Misdiagnosis occurred in 1 (7.7%) patient who suffered from continuous pain and limited knee flexion, and 4 weeks elapsed since the initial injury to being diagnosed.
For all patients, DFCLP was favoured over other fixation devices. Screws were placed according to fracture fragment. The general patient demographic data are shown in Table 1.
Table 1
Demographic data of the patients.
Case
|
Age/Gender
|
Injury Mechanism
|
Fracture subtype
|
Surgical Approach
|
Late diagnosis(weeks)
|
Follow-up(months)
|
1
|
60/F
|
High-velocity fall
|
Ⅲ/MC
|
medial
|
-
|
24
|
2
|
46/M
|
High-velocity fall
|
Ⅱb/LC
|
lateral
|
4
|
24
|
3
|
61/M
|
Motor vehicle accident
|
Ⅰ/LC
|
lateral
|
-
|
26
|
4
|
37/M
|
Motor vehicle accident
|
Ⅱb/MC
|
medial
|
-
|
24
|
5
|
51/M
|
Heavy object smashing
|
Ⅱa/LC
|
lateral
|
-
|
24
|
6
|
52/M
|
Motor vehicle accident
|
Ⅲ/LC
|
lateral
|
-
|
28
|
7
|
64/F
|
High-velocity fall
|
Ⅲ/LC
|
lateral
|
-
|
24
|
8
|
45/M
|
High-velocity fall
|
Ⅱa/LC
|
lateral
|
-
|
24
|
9
|
46/M
|
Motor vehicle accident
|
Ⅲ/LC
|
lateral
|
-
|
24
|
10
|
26/F
|
Motor vehicle accident
|
Ⅰ/LC
|
lateral
|
-
|
24
|
11
|
63/F
|
High-velocity fall
|
Ⅲ/MC
|
medial
|
-
|
24
|
12
|
54/M
|
High-velocity fall
|
Ⅲ/LC
|
lateral
|
-
|
24
|
13
|
44/M
|
High-velocity fall
|
Ⅲ/LC
|
lateral
|
-
|
24
|
M:male F:female MC:medial condyle LC:lateral condyle ACL:anterior cruciate ligament LCL:lateral collateral ligament MCL:medial collateral ligament |
1.2 Surgical management
The operation was performed by professional orthopaedic surgeons. Open reduction through the modified medial or lateral approach was used to treat all fractures. Patients were placed supine on the operating table with the involved knee bent at 60º and a soft pad inserted under the popliteal fossa. Patients were under general or spinal anaesthesia for the surgery; tourniquets were used during the surgery to limit blood flow.
The medial approach incision was made at the level of the femoral adductor tubercle, which was curved parallel to the tibial margin, and the incision was stopped at the lower margin of the tibial plateau. The sartorius anterior margin was identified first and separated along the space between itself and the vastus medialis. Then, the knee was flexed and pulled back the sartorius to expose the adductor magnus tendon and the adductor tubercle, and the adductor magnus tendon was pulled back last to expose the fracture. The lateral incision approach extends downwards along the lateral femoral axis across the lateral femoral condyle, turns to the tibial tubercle, enters along the anterior or posterior side of the iliotibial tract, cuts fascia in front of the lateral muscle septum, and pulls the lateral femoral muscle upward to expose the fracture and articular surface. The hematoma was cleaned, and the articular surface reduced with forceps. The intact fragment of the Hoffa fracture was reduced and temporarily fixed by Kirschner wires in the anteroposterior or posteroanterior position. The direction of Kirschner wire was as far vertical to the fracture line as possible. Biplanar fluoroscopic imaging was used to confirm the reduction.
Afterward, DFCLP or cannulated screws were placed to fix fractures. The ideal screw directions would be perpendicular to the fracture line of the major coronal plane along the longest axis of the medial femoral condyle. There are many sizes of screws that can be used, depending on fracture fragment size, ranging from mini fragment implants (2.0 and 2.4mm) to 3.5mm cortical screws, and 4mm or 6.5mm cannulated screws. Meanwhile, DFCLP was placed on the side of the femoral condyle for preventing the fragment from gliding vertically as well as fixing it with angular stability. However, it should be evaluated accurately how the plate was placed to prevent the screws from interfering with each other. Direct fluoroscopic visualization was then used to confirm the precision of the reduction and implant placement. The stability and motion range of the knee were checked for, followed by the deflation of the tourniquet and closure of the wound over suction drains. No external fixation was used after operation.
During the last follow-up appointment, all patients were assessed using the following methods: PA, physical examination, and lateral radiographs. A goniometer was used to measure the bilateral knee range of motion (ROM) and any restriction was recorded. An independent assessor who was unaware of the types of surgical treatment and fracture carried out all evaluations. The Knee Society Score (KSS) and International Knee Documentation Committee (IKDC) was used to evaluate the functional outcomes. Any stability, type of fixation, bone union time, and complications were noted. The details are presented in Table 2.
Table 2
Functional results and complications of the patients.
Case
|
Fixation
|
Knee ROM(degree)
|
SCORE
|
Bone union time(months)
|
Stability
|
Complications
|
KSS
|
IKDC
|
1
|
Plate and screws
|
0−130
|
88
|
88.5
|
3
|
Stable
|
-
|
2
|
Plate
|
0−120
|
90
|
86.2
|
3
|
Stable
|
-
|
3
|
Plate
|
0−125
|
91
|
87.4
|
4
|
Stable
|
-
|
4
|
Plate
|
0−110
|
86
|
75.9
|
4
|
Stable
|
-
|
5
|
Plate
|
0−115
|
85
|
82.8
|
3
|
Stable
|
-
|
6
|
Plate
|
0−120
|
84
|
81.6
|
3
|
Stable
|
Stiffness
|
7
|
Plate and screws
|
0−120
|
91
|
89.7
|
4
|
Stable
|
-
|
8
|
Plate
|
0−125
|
90
|
85.1
|
3
|
Stable
|
-
|
9
|
Plate and screws
|
0−100
|
80
|
74.7
|
4
|
Stable
|
Stiffness osteoarthritis
|
10
|
Plate
|
0−120
|
88
|
83.9
|
3
|
Stable
|
-
|
11
|
Plate and screws
|
0−120
|
89
|
85.6
|
3
|
Stable
|
-
|
12
|
Plate and screws
|
0−125
|
92
|
87.4
|
4
|
Stable
|
-
|
13
|
Plate and screws
|
0−120
|
90
|
85.2
|
4
|
Stable
|
-
|
ROM:range of motion |
KSS:Knee Society Clinical Score |
IKDC:International Knee Documentation Committee |
1.3 Rehabilitation
In order to restore optimum functions of the injured knee joint, a comprehensive early active rehabilitation program was adhered to. The functional outcome analyses were conducted according to the Knee Society Score (KSS), range of movement (ROM), International Knee Documentation Committee (IKDC), and the fixation stability of the patients.
One of the most crucial targets during the early stage of the postoperative rehabilitation was to minimize swelling and pain, thus elevation of the affected leg combined with non-steroidal anti-inflammatory drugs were recommended. When the pain and swelling subsided, the continuous passive motion (CPM) system was used for helping the knee joints to do extension and flexion exercises in all patients from day 3 postoperatively [2]. On day 7 post-operatively, the degree of knee flexion increased from 0°to 60°. Starting from the 2nd week, the frequency of the exercise was increased to 2 to 3 times a day, to achieve a 10°to 15°advance in the range of knee flexion every day. By the end of week 3 post-operatively, patients were encouraged to reach a milestone of between 100°to 130°of flexion. In the fourth week, patients were allowed to perform a full range of motion for 30 to 40mins 2 to 3 times a day. During weeks 6 to 8 after surgery, patients began practicing walking without bearing weights using crutches, which is followed by partial weight-bearing walks at around week 10. For patients who had been discharged, the weight born was gradually increased following the guidance of the clinician given through telerahabilitation. Full weight-bearing walks were allowed once signs of bone reunion were detected on radiographs from weeks 14 to 28 postoperatively.
After being discharged, patient follow-up was carried out every month for the first 3 months using X-ray or CT imaging, then every 3 months in the following 9 months, and finally at the 12th and 24th months.