Early patellar tendon rupture after total knee arthroplasty: A direct repair method.

BACKGROUND: Patellar tendon rupture after total knee arthroplasty (TKA) is a catastrophic complication. Although the occurrence of this injury is rare, it can lead to significant dysfunction for the patient and is very tricky to deal with. There has been no standard treatment for early patella tendon rupture after TKA, and long-term follow-up data are lacking. AIM: To introduce a direct repair method for early patella tendon rupture following TKA and determine the clinical outcomes and complications of this method. METHODS: During the period of 2008 to 2021, 3265 consecutive TKAs were retrospectively reviewed. Twelve patients developed early patellar tendon rupture postoperatively and were treated by a direct repair method. Mean follow-up was 5.7 years. Demographic, operative, and clinical data were collected. The clinical outcomes were assessed using the Western Ontario and McMaster Universities (WOMAC) score, the Hospital for Special Surgery (HSS) score, knee range of motion, extensor lag, and surgical complications. Descriptive statistics and paired t test were employed to analyze the data. RESULTS: For all 12 patients who underwent direct repair for early patellar tendon rupture, 3 patients failed: One (8.3%) for infection and two (17.6%) for re-fracture. The two patients with re-fracture both underwent reoperation to reconstruct the extensor mechanism and the patient with infection underwent revision surgery. The range of motion was 109.2° ± 10.6° preoperatively to 87.9° ± 11° postoperatively, mean extensor lag was 21° at follow-up, and mean WOMAC and HSS scores were 65.8 ± 30.9 and 60.3 ± 21.7 points, respectively. CONCLUSION: This direct repair method of early patellar tendon rupture is not an ideal therapy. It is actually ineffective for the recovery of knee joint function in patients, and is still associated with severe knee extension lag and high complication rates. Compared with the outcomes of other repair methods mentioned in the literature, this direct repair method shows poor clinical outcomes.

Different squatting positions after total knee arthroplasty: A retrospective study.

BACKGROUND: Total knee arthroplasty (TKA) has been shown to improve quality of life and reduce pain. High-flexion activities such as squatting, kneeling, and floor transfers are mainly listed as demanding tasks. Among them, squatting is an important position. AIM: To provide a new squat position classification and evaluate the different squatting positions of a series of patients after primary TKA. METHODS: From May 2018 to October 2019, we retrospectively reviewed 154 video recordings of the squatting-related motions of patients after TKA. Among the included patients, 119 were women and 35 were men. Their mean age at the index surgery was 61.4 years (range, 30 to 77). RESULTS: The median follow-up was 12 mo (range, 6 to 156 mo). We classified those squatting-related motions into three major variations according to squatting depth: Half squat, parallel squat, and deep squat. The angles of hip flexion, knee flexion, and ankle dorsiflexion were measured in the screenshots captured from the videos at the moment of squatting nadir. A total of 26 patients were classified as half squats, 75 as parallel squats, and 53 as deep squats. The angles of hip flexion, knee flexion, and ankle dorsiflexion all differed significantly among the three squatting positions (P < 0.001). In the parallel squat group, the mean knee flexion angle (°) was 116.5 (SD, 8.1; range, 97 to 137). In the deep squat group, the mean knee flexion angle (°) was 132.5 (SD, 9.3; range, 116 to 158). CONCLUSION: Among the three squatting positions, deep squat showed the highest hip, knee, and ankle flexion angles, followed by the parallel squat. With the improvement of squatting ability, the patient's postoperative satisfaction rate was also significantly enhanced. However, the different squatting abilities of the patients cannot be effectively distinguished from the scoring results (P > 0.05). Our squatting position classification offers a pragmatic approach to evaluating patients' squatting ability after TKA.

Comparison of Preoperative Computed Tomography and Intraoperative Estimation in Predicting the Version of a Single-Wedge Femoral Stem.

OBJECTIVE: Early prediction of stem version aids in optimization of combined version during total hip arthroplasty (THA). This study aimed to analyze the discrepancy between stem version and native femoral version measured by different methods, and to explore which method can better predict the stem version. METHODS: We retrospectively reviewed 26 patients (39 hips) treated with robot-assisted THA in our hospital between September 2019 and December 2019. A straight, single-wedge, cementless stem (Accolade II) was used in all cases. Preoperative femoral version was measured at three levels on computerized tomography (CT) scan from the top to the middle level of femoral neck (Level 1 to Level 3). During THA, the version on cutting surface was measured prior to femoral broaching based on two reference lines: mid-cortical line and T line (trochanteric fossa to the middle of medial cortex). After femoral broaching, stem version was measured based on the femoral neck trial using Mako system (Stryker). In the statistical analysis, the difference and absolute discrepancy between stem version and femoral version measured with various methods were examined using paired t-test, and the relationship between stem version and various femoral versions were examined using correlation analysis. RESULTS: Mean femoral neck version (Level 1) was 9.5° ± 2.6° (range, -16.8°-42.5°), while mean stem version measured by Mako system was 19.9° ± 2.0° (range, -8.0°-49.0°). Femoral version measured with each method showed a moderate correlation with stem version (p < 0.05). There was a significant difference between stem version and femoral version except at Level 3, with a mean difference of 0.8° ± 13.6° (p = 0.729). With regard to the intraoperative estimation, stem version significantly increased compared to the value based on mid-cortical line, with a mean difference of 8.4° ± 13.1° (p < 0.001). However, the mean value of stem version was a little smaller than that of femoral version measured by reference to T line, but without statistical significance (p = 0.156). No postoperative dislocations occurred during the study period. No revision was required for any component. CONCLUSIONS: The middle level of femoral neck on CT scan and T line on cutting surface are better references to measure femoral version for predicting postoperative stem version. However, the relationship between stem version and predictive value was flexible. Therefore, further three-dimensional studies of postoperative CT are needed to validate the press-fit fixation and rotational freedom of the single-wedge stem.

Change of Pelvic Sagittal Tilt after Total Hip Arthroplasty in Patients with Bilateral Crowe Type IV Developmental Dysplasia of the Hip.

OBJECTIVE: To explore and analyze the change of pelvic sagittal tilt (PST) after total hip arthroplasty (THA) in patients with bilateral Crowe type IV developmental dysplasia of the hip (DDH). METHODS: The study retrospectively evaluated 43 patients with bilateral Crowe type IV DDH undergoing THA from January 2008 to June 2019 who were followed up for 12 months postoperatively. Four parameters, including the ratio between the height and width of the obturator foramina(H/W ratio), the vertical distance between the upper edge of the symphysis and the middle of the sacrococcygeal joint (SSc distance), the vertical distance between the upper edge of the symphysis and the line connecting bilateral hip centers (SC distance) and the vertical distance between the upper edge of the symphysis and the line connecting the bilateral lower ends of the sacroiliac joints (SSi distance), which could indirectly reflect the change of PST, were observed and measured by radiographs. The change of each parameter before operation, immediately after operation, and in 3, 6 and 12 months postoperatively was compared and analyzed. RESULTS: Compared with the value before operation, the H/W ratio immediately after operation and in 3, 6 and 12 months postoperatively were 0.61 ± 0.12 (t = 0.893, P = 0.377), 0.61 ± 0.11 (t = 1.622, P = 0.112), 0.67 ± 0.10 (t = 5.995, P < 0.001) and 0.76 ± 0.12 (t = -9.313, P < 0.001), respectively, and the SSc, SC and SSi distance in 6 months postoperatively were 30.12 ± 7.06 mm (t = 3.506, P = 0.002), 42.8 ± 7.7 mm (t = 5.843, P < 0.001), 129.3 ± 12.6 mm (t = 5.888, P < 0.001), respectively, and in 12 months postoperatively were 27.24 ± 7.68 mm (t = 6.510, P < 0.001), 36.1 ± 9.1 mm (t = 9.230, P < 0.001), 118.9 ± 14.9 mm (t = 8.940, P < 0.001), respectively. The radiographs obtained in 6 and 12 months postoperatively demonstrated a significantly increased H/W ratio and decreased SSc, SC and SSi distance. At the last follow-up, the clinical evaluations significantly improved in all patients and there were no revisions. CONCLUSION: The significant change of pelvic sagittal posterior tilt in patients with bilateral Crowe type IV DDH might be a significant phenomenon after THA, which could occur in 6 months postoperatively.

Mass spectral and theoretical investigations of N-Cα bond cleavages in the disulfide-containing peptide TTCPYCKK and its analogues.

RATIONALE: For disulfide-containing peptides, mass spectrometric analyses are rarely comparably studied between their dithiol and disulfide forms. Persulfide ions afforded from peptides with a disulfide ring are from either an unusual N-Cα bond cleavage or a canonical peptide bond cleavage; their isomeric structures are, however, not identified just from peaks of mass spectra. METHODS: Isomeric structures of [C3 P4 X5 |C6 M ], [C3 MA P4 X5 |C6 MB ] and [P4 X5 C6 |C3 M ] were identified from a series of the X5 substituted dicysteine octapeptides using electrospray ionization tandem mass spectrometry for both their dithiol and disulfide forms. Formation mechanisms of different persulfide ions were investigated systematically by theoretical methods. Moreover, electrostatic potential-mapped molecular van der Waals surfaces were used to determine the stabilities of the intermediates, which gave a further evaluation of favored bond cleavage. RESULTS: Mass spectral analyses indicated that the fragmented ions changed largely when an intramolecular disulfide bond was formed. New types of disulfide-containing fragmented ions [C3 P4 X5 |C6 M ] or [C3 MA P4 X5 |C6 MB ] were thus proposed. Energy analysis showed that the N-Cα cleavage was not competitive energetically with that of the amide bond for Y5 and its phosphorylated analogue. However, the N-Cα cleavage products dominated for the S5 - and T5 -containing peptides. Stabilities of the intermediates were found to be related with the electrostatic potential-mapped molecular van der Waals surfaces. CONCLUSIONS: Persulfide ions containing more residues than previously found were proposed not only from b7 ions but also from y6 ions. In addition, a new kind of phosphorylated analogue, [C3 P4 p Y5 |C6 M ], is reported in this work. Our study provides convincing results for separating isomeric structures in the cases of N-Cα cleavages, which greatly assists in the structural identification of disulfide-containing peptides.

[Value of personalized extramedullary positioning technique on tibia side for coronal alignment of tibial prosthesis in total knee arthroplasty].

OBJECTIVE: To explore the coronal alignment of tibial prosthesis after osteotomy using personalized extramedullary positioning technique on tibia side in total knee arthroplasty (TKA). METHODS: A clinical data of 170 patients (210 knees) who underwent primary TKA between January 2020 and June 2021 and met the selection criteria was retrospectively analyzed. Personalized and traditional extramedullary positioning techniques were used in 93 cases (114 knees, personalized positioning group) and 77 cases (96 knees, traditional positioning group), respectively. The personalized extramedullary positioning was based on the anatomical characteristics of the tibia, a personalized positioning point was selected as the proximal extramedullary positioning point on the articular surface of the tibial plateau. There was no significant difference between the two groups in gender, age, body mass index, surgical side, course of osteoarthritis, and Kellgren-Lawrence classification ( P>0.05). The preoperative tibial bowing angle (TBA) formed by the proximal and distal tibial coronal anatomical axes in the personalized positioning group was measured and the tibia axis was classified, and the distribution of personalized positioning point was analyzed. The pre- and post-operative hip-knee-ankle angle (HKA), the lateral distal tibial angle (LDTA), and the postoperative tibia component angle (TCA), the excellent rate of tibial prosthesis alignment in coronal position were compared between the two groups. RESULTS: In the personalized positioning group, 58 knees (50.88%) were straight tibia, 35 knees (30.70%) were medial bowing tibia, and 21 knees (18.42%) were lateral bowing tibia. The most positioning points located on the highest point of the lateral intercondylar spine (62.07%) in the straight tibia group, while in the medial bowing tibia and lateral bowing tibia groups, most positioning points located in the area between the medial and lateral intercondylar spines (51.43%) and the lateral slope of the lateral intercondylar spine (57.14%), respectively. The difference in HKA between pre- and post-operation in the two groups was significant ( P<0.05); while the difference in LDTA was not significant ( P>0.05). There was no significant difference in preoperative LDTA and HKA and the difference between pre- and post-operation between groups ( P>0.05). But there was significant difference in postoperative TCA between groups ( P<0.05). The postoperative tibial plateau prosthesis in the traditional positioning group was more prone to varus than the personalized positioning group. The excellent rates of tibial prosthesis alignment in coronal position were 96.5% (110/114) and 87.5% (84/96) in personalized positioning group and traditional positioning group, respectively, showing a significant difference between groups ( χ 2=7.652, P=0.006). CONCLUSION: It is feasible to use personalized extramedullary positioning technique for coronal osteotomy on the tibia side in TKA. Compared with the traditional extramedullary positioning technique, the personalized extramedullary positioning technique has a higher excellent rate of tibial prosthesis alignment in coronal position.

[Status and treatment of knee extension device disruption after total knee arthroplasty].

OBJECTIVE: To summarize the principle, classification, and treatment methods of knee extension device disruption after total knee arthroplasty (TKA). METHODS: By extensively consulted the relevant domestic and abroad literature, the principle, classification, and treatment methods of injury according to different parts of the knee extension device after TKA were summarized and analyzed. RESULTS: The knee extension device disruption after TKA mainly occurs in the quadriceps tendon, patella tendon, and patella. Once the knee extension device is injured, it will seriously affect the functional recovery of the patient after surgery, resulting in delayed knee extension, limited range of motion, difficulty walking, and joint pain, etc. The current treatment methods are diverse, including conservative treatment and surgical treatment. Surgical treatment includes direct suture repair (traditional perosseous fixation and suture anchoring techniques), reconstruction and reinforcement repair (reconstruction using synthetic patches, autografts, and allografts). For the treatment of different parts, it is necessary to comprehensively consider the patient's knee joint tissue condition, the presence or absence of underlying diseases, and the presence or absence of donors. CONCLUSION: There is no uniform conclusion on the treatment of knee extension device disruption after TKA. Different injury situations need to be considered comprehensively to choose the appropriate treatment method.

Functional and radiographical results of asymmetrically reconstructed total hip arthroplasty in patients with bilateral dysplastic arthritic hips with one hip Crowe II-III and the other Crowe IV: a retrospective cohort study.

BACKGROUND: The study aimed to evaluate the functional and radiographical results of asymmetrically reconstructed total hip arthroplasty in patients with bilateral dysplastic arthritic hips with one hip Crowe II-III and the other hip Crowe IV. MATERIALS AND METHODS: From April 2006 to April 2019, we evaluated 23 patients who had a reconstruction of one Crowe II-III hip with high hip center (HHC) and the other Crowe IV hip at the anatomical position (H group). The radiographic and clinical outcomes were compared with those of a control group of 19 patients with bilateral dysplasia who had one Crowe IV hip and the contralateral hip both reconstructed in the anatomical position (A group). Medical records and radiographs were reviewed, and a complete follow-up was conducted for all patients. RESULTS: The mean vertical center of rotation (V-COR) and horizontal center of rotation (H-COR) in the H group were 30.6 ± 5.8 mm and 30.0 ± 5.5 mm, respectively. In the A group, the corresponding values were 14.0 ± 4.3 mm and 23.0 ± 2.3 mm, respectively. A significant difference was found in terms of V-COR and H-COR between the two groups, and no significant difference was shown regarding the cup inclination, abductor lever arm (ALA), ALA ratio, and leg length discrepancy (LLD). Three patients of the H group and four patients of the A group exhibited LLD > 10 mm. All seven patients who had LLD > 10 mm underwent the shortening subtrochanteric osteotomy (SSTO) of the Crowe IV hip. Subgroup analysis based on the presence and absence of SSTO showed that the LLD of the SSTO group was greater than that of the non-SSTO group in both groups, but the difference was only statistically significant in the A group. At the last follow-up, the mean Harris Hip Scores significantly improved in the two groups, and there was no revision during the follow-up period. In the H group, four patients presented with a slight limp and three patients with a moderate limp, while it was six patients and one patient in the A group, respectively. CONCLUSIONS: Asymmetrical reconstruction in patients with bilateral dysplastic arthritic hips with one hip Crowe II-III and the other Crowe IV is acceptable and comparable when compared with bilateral anatomical reconstruction. LEVEL OF EVIDENCE: III, retrospective observational study. Trial registration Chinese Clinical Trail Registry. ChiCTR2000033848.

Single-stage total knee arthroplasty and femoral osteotomy for osteoarthritis with severe supracondylar deformity.

BACKGROUND: Knee osteoarthritis associated with extra-articular deformity (EAD) can confront the arthroplasty surgeons with challenges of bone resection and soft tissue balancing. The aim of this study was to describe a single-stage procedure associating corrective osteotomy with total knee arthroplasty (TKA), and to determine the outcome at mid- to long-term follow-up. METHODS: A total of seven patients (seven knees) with knee osteoarthritis and supracondylar deformity were included in this study. Six patients were female, and one was male, with the median age of 62 years (range, 37-76 years). All patients were treated with single-stage TKA and femoral osteotomy. Osteotomy was fixed with long cemented stem. Hospital of Special Surgery (HSS) scores, collateral ligament laxity, and range of motion (ROM) were clinically evaluated preoperatively and at each follow-up. Radiographic parameters including the mechanical axis deviation (MAD), mechanical lateral distal femoral angle (mLDFA), mechanical proximal tibial angle (mMPTA), and joint line congruence angle (JLCA) were also measured. The occurrence of perioperative complications was recorded. RESULTS: The median follow-up time was 91 months (range, 38-104 months). At the last follow-up, all components were stable and no patients required revision. Nonunion of the osteotomy occurred in one patient. In all patients, the lower limb mechanical alignment improved greatly. The mean angle of MAD was restored from 10.49±6.05 cm preoperatively to 1.11±4.97 cm postoperatively. The 90° mLDFA was almost acquired in all cases, with the postoperative value of 90.79±2.40°. After operation, the mMPTA improved from 84.18±6.13° to 91.33±3.13°. The JLCA changed from 2.94±1.61° to -0.71±3.50°. The median HSS score improved from 45 (range, 34-56) preoperatively to 90 (range, 82-97) postoperatively, with the outcome of all patients rated good to excellent. The median ROM improved from 70° (range 0-110°) preoperatively to 105° (range 90-125°) postoperatively. No instability of knee joint was observed. Complications included an intraoperative split fracture of distal femur and one case of wound exudation resulting from fat liquefaction. CONCLUSIONS: For knee osteoarthritis with femoral supracondylar deformity, single-stage TKA and corrective osteotomy was feasible but technically demanding. The use of long cemented stem for osteotomy fixation can provide reliable rotational control of the bone segments.

[Prevention and treatment of iatrogenic medial collateral ligament injuries in total knee arthroplasty].

OBJECTIVE: To summarize the prevention and treatment of iatrogenic medial collateral ligament (MCL) injuries in total knee arthroplasty (TKA). METHODS: The relevant literature about iatrogenic MCL injuries in TKA was summarized, and the symptoms, causes, preventions, and treatments were analyzed. RESULTS: Preventions on the iatrogenic MCL injuries in TKA is significantly promoted. With the occurrence of MCL injuries, the femoral avulsion can be fixed with the screw and washer or the suture anchors; the tibial avulsion can be treated with the suture anchors fixation, bone staples fixation, or conservative treatment; the mid-substance laceration can be repaired directly; the autologous quadriceps tendon, semitendinosus tendon, or artificial ligament can be used for the patients with poor tissue conditions or obvious residual gap between the ligament ends; the use of implant with greater constraint can be the last alternative method. CONCLUSION: No consensus has been reached to the management of iatrogenic MCL injuries in TKA. Different solutions and strategies can be integrated and adopted flexibly by surgeons according to the specific situation.

Model to Predict Need for Subtrochanteric Shortening Osteotomy During Total Hip Arthroplasty for Crowe Type IV Developmental Dysplasia.

BACKGROUND Indications for subtrochanteric shortening osteotomy (SSOT) during Crowe type IV developmental dysplasia of the hip (DDH) are unclear. The aim of this retrospective study was to create a model to predict the need for performing SSOT. MATERIAL AND METHODS One hundred forty-nine patients (186 hips) with Crowe Type IV DDH who underwent total hip arthroplasty (THA) with S-ROM implants from January 2010 to November 2018 were included in the study. The acetabular components were placed at the true acetabulum and the trial femoral component was inserted. Reduction then was attempted and if it could not be achieved, SSOT was performed. Using multivariable Cox regression analysis, a model was constructed that included age, sex, surgical history, use of a cone- or triangle-shaped sleeve, secondary acetabulum formation, and percentage of dislocation as predictive factors for SSOT. RESULTS SSOTs were performed on 140 of 186 hips. Secondary acetabulum formation was present in 27 hips (58.70%) in which SSOT was not performed 7 (5.00%) in which it was performed. Cone-shaped sleeves were used in 17 hips (36.96%) in which SSOT was not performed versus 15 (10.71%) hips in which it was performed. Dislocation occurred in 31.30±5.80% hips in which SSOT was performed versus 24.05±4.39% of those in which it was not performed. Percentage of dislocation was associated with an increased likelihood of SSOT (odds ratio [OR] 1.24, 95% confidence interval 1.11-1.38), whereas secondary acetabulum formation (OR 0.10, 0.03-0.33) and use of a cone-shaped sleeve (0.18, 0.06-0.53) were associated with decreased likelihood of SSOT. We established a model for prediction of SSOT with a nanogram and the discriminative ability (C statistic) of it was 0.918 (0.79-0.92). CONCLUSIONS Factors that significantly affect likelihood of performing an SSOT were identified and a model with significant ability to predict the need for SSOT in patients with Crowe Type IV DDH was created.

High Hip Center Technique in Total Hip Arthroplasty for Crowe Type II-III Developmental Dysplasia: Results of Midterm Follow-up.

OBJECTIVES: We aimed to show the utility of high hip center technique used in patients with Crowe II-III developmental dysplasia of the hip at the midterm follow-up and evaluated the clinical and radiographic results between different heights of hip center. METHODS: From December 2003 to November 2013, we retrospectively evaluated 69 patients (85 hips) with Crowe II-III dysplasia who underwent a high hip center cementless total hip arthroplasty. The patients were divided into two groups according to the height of hip center, respectively group A (≥ 22 mm and < 28 mm) and group B (≥28 mm). The survivorship outcomes and radiographic and clinical results, including the vertical and horizontal distances of hip center, femoral offset, abductor lever arm, cup inclination, leg length discrepancy, Trendelenburg sign, and limp were evaluated. RESULTS: The mean follow-up time was 8.9 ± 1.8 years. The mean location of the hip center from the inter-teardrop was 25.1 ± 1.6 mm vertically and 30.0 ± 3.8 mm horizontally in group A, and 33.1 ± 4.8 mm vertically and 31.4 ± 6.1 mm horizontally in group B. Eleven hips of group B showed a lateralization over 10 mm, and the same was shown in one hip in group A (P = 0.012). There were no statistically significant differences between two groups in postoperative femoral offset, abductor lever arm, leg length discrepancy and cup inclination. At the final follow up, the mean WOMAC and Harris hip score were significantly improved in both groups. Of the 85 hips, four hips in group A and three hips in group B showed a positive Trendelenburg sign. Additionally, four patients in group A and two patients in group B presented with a limp. No significant differences were shown regarding the Harris hip score, WOMAC score, Trendelenburg sign, and limp between two groups. One hip of group A was revised by reason of dislocation at 8.3 years after surgery. One hip of group B was diagnosed with osteolysis and underwent a revision at 8.1 years after surgery. The Kaplan-Meier implants survivorship rates at the final follow-up for all-causes revisions in group A and group B were similar (96.7% [95% confidence interval, 90.5%-100%] and 96.2% [95% confidence interval, 89.0%-100%], respectively). CONCLUSIONS: The high hip center technique is a valuable alternative to achieve excellent midterm results for Crowe II-III developmental dysplasia of the hip. Further, between the groups with differing degrees of HHC, there were no significant differences in outcomes or survivorship in our study.

The Effect of the False Acetabulum on Femoral Proximal Medullary Canal in Unilateral Crowe Type IV Developmental Dislocation of the Hip.

PURPOSE: To investigate the effect of the false acetabulum on femoral proximal medullary canal in unilateral Crowe type IV developmental dislocation of the hip (DDH) patients on anteroposterior radiographs. PATIENTS AND METHODS: We measured the following parameters of DDH and contralateral normal hip (CNH) of proximal morphology of femurs on 65 patients with unilateral Crowe type IV DDH (30 hips with no false acetabulum (type IVA) and 35 hips with a false acetabulum (type IVB)) in our hospital between September 2009 and July 2019 on anteroposterior radiographs: the widths of medullary canals at 20 mm above the center of lesser trochanter (CLT), 20 mm below the CLT and the isthmus. Canal flare index (CFI), metaphyseal canal flare index (MCFI), diaphyseal canal flare index (DCFI) were calculated. RESULTS: The values of CFI of DDH and CNH in unilateral type IVA patients were 2.8 and 4.4, respectively (p < 0.001), and those in type IVB patients were 3.9 and 4.6, respectively (p < 0.001). The MCFIs of DDH and CNH in type IVA group were 2.2 and 2.3, respectively (p = 0.032), and those in type IVB group were 2.4 and 2.4, respectively (p = 0.242). The DCFIs of DDH and CNH in type IVA group were 1.3 and 1.9, respectively (p < 0.001), and those in type IVB group were 1.7 and 1.9, respectively (p = 0.002). CONCLUSION: The false acetabulum stimulated the development of the proximal femur in Crowe type IV DDH. The variation of the femoral proximal medullary canal in type IVA DDH mainly occurred at the metaphyseal and proximal diaphyseal levels, and that in type IVB DDH mainly occurred at the proximal diaphyseal level.